Effective Network Programming in iOS 7

Presented at Mobile Developer Summit Oct 11th in Bangalore, India

Transcript

1. Effective Network
   Programming
   with
   iOS 7
   Wednesday, October 9, 13
   

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2. Ben Scheirman
   CFOTDIFJSNBODPN !TVCEJHJUBM
   • Director

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3. Wednesday, October 9, 13
   

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4. Bite-sized Screencasts
   .com
   Weekly

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5. Why is this important?
   99%

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6. Why is this important?
   Doing

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7. Why is this important?
   Too

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8. Exhibit A: Stuttery Scroller
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9. Exhibit A: Stuttery Scroller
   Accessing

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10. Exhibit B: The Perpetual Loader
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11. Exhibit B: The Perpetual Loader
    How

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12. Exhibit C: Slow Loader
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13. Exhibit C: Slow Loader
    Loading

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14. Exhibit D: Yesterday’s News
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15. Exhibit D: Yesterday’s News
    Caching

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16. What we’ll cover
    w /463-4FTTJPO#BTJDT
    w -*7&$0%*/( XJTINFMVDL
    
    w "'/FUXPSLJOH
    w )551$BDIJOH
    w $BDIJOH1BUUFSOT
    w "1*%FTJHO5JQT
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17. NSURLConnection
    Invented for Safari ~2000, made
    public in 2003
    Poor separation of settings,
    config, cache
    Now replaced by NSURLSession
    classes
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18. NSURLConnection
    Invented for Safari ~2000, made
    public in 2003
    Poor separation of settings,
    config, cache
    Now replaced by NSURLSession
    classes
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19. NSURLSession
    Still use NSURLRequest
    Configurable Container (isolation w/ 3rd party libraries)
    Improved auth
    Rich Callbacks
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20. NSURLSession
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21. NSURLSession
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22. NSURLSession
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23. NSURLSession Class Family
    NSURLSessionConfiguration
    NSURLSessionTask
    NSURLSessionDelegate
    NSURLSession
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24. NSURLSession
    NSURLSession
    Interface for issuing network calls against a server
    Likely use case: 1 session per API
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25. NSURLSessionDelegate
    Delegate methods for a session:
    Used for connect level authentication challenges
    NTLM, Kerberos, Client certificates
    - URLSession:didBecomeInvalidWithError:
    - URLSession:didReceiveChallenge:completionHandler:
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26. NSURLSessionTask
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27. NSURLSessionTaskDelegate
    Delegate methods for a request:
    Only need to implement for fine-grained control
    - URLSession:task:willPerformHTTPRedirection:newRequest:completionHandler:
    - URLSession:task:didReceiveChallenge:completionHandler:
    - URLSession:task:needNewBodyStream:
    - URLSession:task:didSendBodyData:totalBytesSent:totalBytesExpectedToSend:
    - URLSession:task:didCompleteWithError:
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28. NSURLSessionDataTaskDelegate
    Delegate methods for a data request:
    Only need to implement for fine-grained control
    - URLSession:dataTask:didReceiveChallenge:completionHandler:
    - URLSession:dataTask:didBecomeDownloadTask:
    - URLSession:dataTask:didReceiveData:
    - URLSession:dataTask:willCacheResponse:completionHandler:
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29. NSURLSessionDownloadDelegate
    - URLSession:downloadTask:didFinishDownloadingToURL:
    -URLSession:downloadTask:didWriteData:totalBytesWritten:totalBytesExpectedToWrite:
    - URLSession:downloadTask:didResumeAtOffset:expectedTotalBytes:
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30. Requesting Images
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31. Have you ever seen this?
    NSURL *imageUrl = [NSURL URLWithString:
    @”http://i.imgur.com/kwpjYwQ.jpg”];
    NSData *imageData = [NSData
    dataWithContentsOfURL:imageUrl];
    UIImage *image = [UIImage imageWithData:imageData];
    [imageView setImage:image];
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32. Have you ever seen this?
    NSURL *imageUrl = [NSURL URLWithString:
    @”http://i.imgur.com/kwpjYwQ.jpg”];
    NSData *imageData = [NSData
    dataWithContentsOfURL:imageUrl];
    UIImage *image = [UIImage imageWithData:imageData];
    [imageView setImage:image];
    WRONG
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33. Have you ever seen this?
    NSURL *imageUrl = [NSURL URLWithString:
    @”http://i.imgur.com/kwpjYwQ.jpg”];
    NSData *imageData = [NSData
    dataWithContentsOfURL:imageUrl];
    UIImage *image = [UIImage imageWithData:imageData];
    [imageView setImage:image];
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34. In case you were wondering...
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35. Demo
    •Demo: Download an image with
    NSURLSessionDownloadTask
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36. NSURLSessionDataTask
    •Represents GET/PUT/POST/DELETE
    •Handle completion callback
    •If error is present, request failed
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37. What constitutes an error?
    • Connection failed
    • Timeouts
    • Host invalid
    • Bad URL
    • Too many redirects
    • ... dozens more (check URL Loading System Error Codes)
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38. Demo
    •Demo: Searching the iTunes Store
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39. AFNetworking
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40. AFNetworking
    2.0
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41. Installation
    gem install cocoapods
    Podfile
    pod install
    platform :ios, "7.0"
    pod 'AFNetworking', '2.0'
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42. Installation
    gem install cocoapods
    Podfile
    pod install
    platform :ios, "7.0"
    pod 'AFNetworking', '2.0'
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43. Installation
    Podfile
    pod install
    platform :ios, "7.0"
    pod 'AFNetworking', '2.0'
    gem install cocoapods
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44. Installation
    Podfile
    pod install
    platform :ios, "6.0"
    pod 'AFNetworking'
    platform :ios, "7.0"
    pod 'AFNetworking', '2.0'
    gem install cocoapods
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45. AFNetworking 1.0 Design
    AFHTTPRequestOperation
    NSOperation
    AFURLConnectionOperation
    NSURLRequest
    NSURLConnection
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46. AFNetworking 2.0 Design
    AFHTTPSessionManager
    NSObject
    AFURLSessionManager NSURLSession
    NSURLSessionConfiguration
    NSURLSessionTask
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47. Serializers
    AFJSONSerializer
    AFURLSessionManager
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48. Usage
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49. Usage
    NSURL *url = [NSURL URLWithString:@”http://google.com”];
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50. Usage
    NSURL *url = [NSURL URLWithString:@”http://google.com”];
    NSURLSessionConfiguration *config = [NSURLSessionConfiguration
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51. Usage
    NSURL *url = [NSURL URLWithString:@”http://google.com”];
    NSURLSessionConfiguration *config = [NSURLSessionConfiguration
    defaultConfiguration];
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52. Usage
    NSURL *url = [NSURL URLWithString:@”http://google.com”];
    NSURLSessionConfiguration *config = [NSURLSessionConfiguration
    defaultConfiguration];
    AFHTTPSessionManager *manager = [[AFHTTPSessionManager alloc]
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53. Usage
    NSURL *url = [NSURL URLWithString:@”http://google.com”];
    NSURLSessionConfiguration *config = [NSURLSessionConfiguration
    defaultConfiguration];
    AFHTTPSessionManager *manager = [[AFHTTPSessionManager alloc]
    initWithSessionConfiguration:config];
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54. Usage
    NSURL *url = [NSURL URLWithString:@”http://google.com”];
    NSURLSessionConfiguration *config = [NSURLSessionConfiguration
    defaultConfiguration];
    AFHTTPSessionManager *manager = [[AFHTTPSessionManager alloc]
    initWithSessionConfiguration:config];
    manager.responseSerializer = [[AFJSONSerializer alloc] init];
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55. Usage
    NSURL *url = [NSURL URLWithString:@”http://google.com”];
    NSURLSessionConfiguration *config = [NSURLSessionConfiguration
    defaultConfiguration];
    AFHTTPSessionManager *manager = [[AFHTTPSessionManager alloc]
    initWithSessionConfiguration:config];
    manager.responseSerializer = [[AFJSONSerializer alloc] init];
    [manager GET:url parameters:nil completion:^(NSURLSessionDataTask *task,
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56. Usage
    NSURL *url = [NSURL URLWithString:@”http://google.com”];
    NSURLSessionConfiguration *config = [NSURLSessionConfiguration
    defaultConfiguration];
    AFHTTPSessionManager *manager = [[AFHTTPSessionManager alloc]
    initWithSessionConfiguration:config];
    manager.responseSerializer = [[AFJSONSerializer alloc] init];
    [manager GET:url parameters:nil completion:^(NSURLSessionDataTask *task,
    id responseObject) {
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57. Usage
    NSURL *url = [NSURL URLWithString:@”http://google.com”];
    NSURLSessionConfiguration *config = [NSURLSessionConfiguration
    defaultConfiguration];
    AFHTTPSessionManager *manager = [[AFHTTPSessionManager alloc]
    initWithSessionConfiguration:config];
    manager.responseSerializer = [[AFJSONSerializer alloc] init];
    [manager GET:url parameters:nil completion:^(NSURLSessionDataTask *task,
    id responseObject) {
    // handle success
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58. Usage
    NSURL *url = [NSURL URLWithString:@”http://google.com”];
    NSURLSessionConfiguration *config = [NSURLSessionConfiguration
    defaultConfiguration];
    AFHTTPSessionManager *manager = [[AFHTTPSessionManager alloc]
    initWithSessionConfiguration:config];
    manager.responseSerializer = [[AFJSONSerializer alloc] init];
    [manager GET:url parameters:nil completion:^(NSURLSessionDataTask *task,
    id responseObject) {
    // handle success
    } failure:^(NSURLSessionDataTask *task, NSError *error) {
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59. Usage
    NSURL *url = [NSURL URLWithString:@”http://google.com”];
    NSURLSessionConfiguration *config = [NSURLSessionConfiguration
    defaultConfiguration];
    AFHTTPSessionManager *manager = [[AFHTTPSessionManager alloc]
    initWithSessionConfiguration:config];
    manager.responseSerializer = [[AFJSONSerializer alloc] init];
    [manager GET:url parameters:nil completion:^(NSURLSessionDataTask *task,
    id responseObject) {
    // handle success
    } failure:^(NSURLSessionDataTask *task, NSError *error) {
    // handle failure
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60. Usage
    NSURL *url = [NSURL URLWithString:@”http://google.com”];
    NSURLSessionConfiguration *config = [NSURLSessionConfiguration
    defaultConfiguration];
    AFHTTPSessionManager *manager = [[AFHTTPSessionManager alloc]
    initWithSessionConfiguration:config];
    manager.responseSerializer = [[AFJSONSerializer alloc] init];
    [manager GET:url parameters:nil completion:^(NSURLSessionDataTask *task,
    id responseObject) {
    // handle success
    } failure:^(NSURLSessionDataTask *task, NSError *error) {
    // handle failure
    }];
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61. Requesting Images
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62. Requesting Images
    NSURL *imageUrl = [NSURL URLWithString:
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63. Requesting Images
    NSURL *imageUrl = [NSURL URLWithString:
    @”http://i.imgur.com/kwpjYwQ.jpg”];
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64. Requesting Images
    NSURL *imageUrl = [NSURL URLWithString:
    @”http://i.imgur.com/kwpjYwQ.jpg”];
    [imageView setImageWithURL:imageUrl];
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65. Requesting XML?
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66. Requesting XML?
    AFXMLResponseSerializer
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67. Requesting plist?
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68. Requesting plist?
    AFPropertyListResponseSerializer
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69. Requesting a custom data format?
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70. Requesting a custom data format?
    MyCustomResponseSerializer
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71. Demo: app.net client
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72. Other AFNetworking Goodies
    AFHTTPSessionManager setSecurityPolicy
    [AFSecurityPolicy policyWithPinningMode:AFSSLPinningModePublicKey]
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73. Other AFNetworking Goodies
    UIActivityIndicatorView+AFNetworking.h
    [indicator setAnimatingWithStateOfTask:task]
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74. HTTP Status Code Cheat Sheet
    1xx - Not Used
    2xx - Thumbs Up
    3xx - It's over there
    4xx - You messed up
    5xx - We messed up
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75. HTTP Caching
    Client Server
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76. HTTP Caching
    Client Server
    GET /customer/152.json HTTP 1.1
    Host: example.com
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77. HTTP Caching
    Client Server
    HTTP/1.1 200 OK
    Content-Type: application/json
    Content-Length: 37142
    Etag:“e6482391249374127ca94128”
    Cache-Control:max-age=60, public
    Date:Sun, 21 Oct 2012 16:15:37
    GET /customer/152.json HTTP 1.1
    Host: example.com
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78. HTTP Caching
    GET /customer/152.json HTTP 1.1
    Host: example.com
    Client Server
    HTTP/1.1 200 OK
    Content-Type: application/json
    Content-Length: 37142
    Etag:“e6482391249374127ca94128”
    Cache-Control:max-age=60, public
    Date:Sun, 21 Oct 2012 16:15:37
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79. HTTP Caching
    GET /customer/152.json HTTP 1.1
    Host: example.com
    Client Server
    HTTP/1.1 200 OK
    Content-Type: application/json
    Content-Length: 37142
    Etag:“e6482391249374127ca94128”
    Cache-Control:max-age=60, public
    Date:Sun, 21 Oct 2012 16:15:37
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80. HTTP Caching
    GET /customer/152.json HTTP 1.1
    Host: example.com
    Client Server
    HTTP/1.1 200 OK
    Content-Type: application/json
    Content-Length: 37142
    Etag:“e6482391249374127ca94128”
    Cache-Control:max-age=60, public
    Date:Sun, 21 Oct 2012 16:15:37
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81. Leveraging Etag on the client
    Client Server
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82. Leveraging Etag on the client
    GET /customer/152.json HTTP 1.1
    Host: example.com
    If-None-Match:“e6482391249374127ca94128”
    Client Server
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83. Leveraging Etag on the client
    GET /customer/152.json HTTP 1.1
    Host: example.com
    If-None-Match:“e6482391249374127ca94128”
    Client Server
    HTTP/1.1 304 Not Modified
    < no response body >
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84. Leveraging Modified Date
    Client Server
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85. Leveraging Modified Date
    GET /customer/152.json HTTP 1.1
    Host: example.com
    If-Modified-Since:
    Client Server
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86. Leveraging Modified Date
    GET /customer/152.json HTTP 1.1
    Host: example.com
    If-Modified-Since:
    Client Server
    HTTP/1.1 304 Not Modified
    < no response body >
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87. Etag/Last Modified on the Server
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88. Etag/Last Modified on the Server
    def show
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89. Etag/Last Modified on the Server
    def show
    @band = Band.find(params[:id])
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90. Etag/Last Modified on the Server
    def show
    @band = Band.find(params[:id])
    fresh_when(:etag => @band,
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91. Etag/Last Modified on the Server
    def show
    @band = Band.find(params[:id])
    fresh_when(:etag => @band,
    :last_modified => @band,
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92. Etag/Last Modified on the Server
    def show
    @band = Band.find(params[:id])
    fresh_when(:etag => @band,
    :last_modified => @band,
    :public => true)
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93. Etag/Last Modified on the Server
    def show
    @band = Band.find(params[:id])
    fresh_when(:etag => @band,
    :last_modified => @band,
    :public => true)
    expires_in 10.minutes, :public => true
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94. Etag/Last Modified on the Server
    def show
    @band = Band.find(params[:id])
    fresh_when(:etag => @band,
    :last_modified => @band,
    :public => true)
    expires_in 10.minutes, :public => true
    end
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95. Etag/Last Modified on the Server
    def show
    @band = Band.find(params[:id])
    fresh_when(:etag => @band,
    :last_modified => @band,
    :public => true)
    expires_in 10.minutes, :public => true
    end
    Note: server still does a db query,
    but doesn’t render a template
    Saves on rendering & bandwidth for response transfer
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96. Cache-Control limitations
    Server
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97. Cache-Control limitations
    Server
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98. Cache-Control limitations
    Server
    Cache-Control: max-age: 600
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99. Cache-Control limitations
    Server
    Cache-Control: max-age: 600
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100. Cache-Control limitations
     Server
     Cache-Control: max-age: 600 Cache-Control: max-age: 600
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101. Reverse-Proxy Cache FTW
     Server
     Varnish / Squid / Nginx
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102. Reverse-Proxy Cache FTW
     Server
     Varnish / Squid / Nginx
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103. Reverse-Proxy Cache FTW
     Server
     Varnish / Squid / Nginx
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104. Reverse-Proxy Cache FTW
     Server
     Cache-Control: max-age: 600
     Varnish / Squid / Nginx
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105. Reverse-Proxy Cache FTW
     Server
     Cache-Control: max-age: 600
     Varnish / Squid / Nginx
     Cache-Control: max-age: 600
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106. Reverse-Proxy Cache FTW
     Server
     Cache-Control: max-age: 600
     Varnish / Squid / Nginx
     Cache-Control: max-age: 600
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107. Reverse-Proxy Cache FTW
     Server
     Cache-Control: max-age: 600
     Cache-Control: max-age: 600
     Varnish / Squid / Nginx
     Cache-Control: max-age: 600
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108. Leverage Cache-Control?
     HTTP/1.1 200 OK
     Content-Type: application/json
     Content-Length: 37142
     Etag:“e6482391249374127ca94128”
     Cache-Control:max-age=9999999999, public
     Date:Sun, 21 Oct 2012 16:15:37 GMT
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109. .JLF %PO`UFWFSDBMMNFBHBJO
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110. Pros / Cons of Cache-Control
     Client doesn’t wait for response
     Server spends no resources
     But, clients may render stale data
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111. Pros / Cons of Etag / IMS
     Server skips rendering
     Miniscule data transfer
     Appears instantaneous*
     But, server still doing a db query
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112. Reason about your data
     • List of US States
     • User’s Profile
     • Customer’s Order
     • Activity Timeline
     • Yesterday’s stats
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113. Tradeoff
     Fresh

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114. Caching w/ NSURLSession
     Leverages NSURLCache
     already
     Use default session configuration or customize cache
     settings
     Use ephemeral configuration to disable caching
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115. Caching w/ NSURLSession
     Customize if needed
     NSURLCache *cache =
     [[NSURLCache alloc] initWithMemoryCapacity:1024*1024*10
     diskCapacity:1024*1024*50
     diskPath:nil];
     [sessionConfiguration setURLCache:cache];
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116. Default Cache Location
     ~/Library/Caches/com.acme.app/Cache.db
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117. Wednesday, October 9, 13
     

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118. Switcheroo
     View Controller API Client
     Coordinator
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119. Switcheroo
     View Controller API Client
     Coordinator
     get data
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120. Switcheroo
     View Controller API Client
     Coordinator
     get data
     start request
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121. Switcheroo
     View Controller API Client
     Coordinator
     get data
     start request
     (cached data)
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122. Switcheroo
     View Controller API Client
     Coordinator
     get data
     start request
     (cached data)
     HTTP GET
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123. Switcheroo
     View Controller API Client
     Coordinator
     get data
     start request
     (cached data)
     HTTP GET
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124. Switcheroo
     View Controller API Client
     Coordinator
     get data
     start request
     (cached data)
     HTTP GET
     200 OK
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125. Switcheroo
     View Controller API Client
     Coordinator
     get data
     start request
     (cached data)
     HTTP GET
     200 OK
     (parsed response)
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126. Switcheroo
     View Controller API Client
     Coordinator
     get data
     start request
     (cached data)
     HTTP GET
     200 OK
     (parsed response)
     update cache
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127. Switcheroo
     View Controller API Client
     Coordinator
     get data
     start request
     (cached data)
     HTTP GET
     200 OK
     (parsed response)
     (parsed response)
     update cache
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128. API Design Tips
     Don’t expose your internal model
     http://www.myspace.com/na6_build/photos/20613762
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129. API Design Tips
     Version your API
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130. API Design Tips
     Send OS Version, App Version,
     and Device Name as headers
     Device Name
     OS Version
     App Version
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131. API Design Tips
     Have a way to notify clients
     to upgrade (even force)
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132. API Design Tips
     • Techniques for permeating deletes
     • Valid ID Check
     • Client requests changes, server returns a set of new
     records, changed records, and deleted record ids
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133. API Design Tips
     Page Large Datasets
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134. API Design Tips
     Build-in HTTP Caching support
     from day 1
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135. API Design Tips
     Take care when caching
     user-specific data
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136. API Design Tips
     Turn on Gzip Compression
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137. API Design Tips
     Measure your API response
     times
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138. Thank you!
     Ben Scheirman
     @subdigital
     @bens (adn)
     @nsscreencast
     Wednesday, October 9, 13
     

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