Good Intentions: A Path to Better View Controllers

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Good Intentions A Path to Building Better ViewControllers Jay Thrash @jaythrash ! 360iDev, Denver August 2014

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We need to talk…

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Model View Controller

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Massive View Controller

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View Controller Misused

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View Controller Mistreated

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Delegate (v) Delegate (n)

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I need _______________________ a DataSource for this TableView ViewController A day in the Life

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I need _______________________ data fetched from the server ViewController A day in the Life

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I need _______________________ someone to validate the form ﬁelds ViewController A day in the Life

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I need _______________________ a CLLocationManagerDelegate ViewController A day in the Life

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I need _______________________ just one more thing. It’s wafer thin. ViewController A day in the Life

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It’s too much

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It’s too much We can do better

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Separation of Concerns Single Responsibility Principal Apply Two Principals

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Stores Techniques 3 Delegate(v) the DataSources Intentions

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Stores Encapsulates access to external sources of data.

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Stores Encapsulates access to external sources of data. Manage Shared Resources ➡ Data Loading & Caching ➡ System Resources ➡ Network ➡ Location ➡ Motion Services ➡ Camera

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Stores #import @class MJTLocation; @interface MJTLocationStore : NSObject + (MJTLocationStore *)store; - (MJTLocation *)locationById:(NSString*)locationId; @end

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Stores #import @class MJTLocation; @interface MJTLocationStore : NSObject + (MJTLocationStore *)store; - (MJTLocation *)locationById:(NSString*)locationId; @end loc = [[MJTLocationStore store] locationById:id];

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Stores Candidates for Stores ! ➡Web Services ➡Databases ➡Filesystem ➡Location/Motion Services ➡Camera

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Delegate the DataSources

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“Lighter View Controllers” obj.io Issue #1 ! ➡ Remove UITableViewDataSource responsibilities from ViewController ! ➡ Encapsulate into own class Delegate the DataSources

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Delegate the DataSources -(id)itemAtIndexPath:(NSIndexPath*)indexPath {} -(NSInteger)numberOfSectionsInTableView:(UITableView *)tv -(NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section -(UITableViewCell *)tableView:(UITableView *)tv cellForRowAtIndexPath:(NSIndexPath *)indexPath Typical DataSource Pattern

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Delegate the DataSources -(id)itemAtIndexPath:(NSIndexPath*)indexPath {} ! -(NSInteger)numberOfSectionsInTableView:(UITableView *)tv ! -(NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section ! -(UITableViewCell *)tableView:(UITableView *)tv cellForRowAtIndexPath:(NSIndexPath *)indexPath Typical DataSource Pattern

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Delegate the DataSources DataSource

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Backing Store ViewController Delegate the DataSources DataSource

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Backing Store ViewController Delegate the DataSources DataSource

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Backing Store ViewController Delegate the DataSources DataSource

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Backing Store ViewController Delegate the DataSources DataSource @[x, y, z]

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Backing Store ViewController Delegate the DataSources DataSource @[x, y, z] plist

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Backing Store ViewController Delegate the DataSources DataSource @[x, y, z] plist CoreData

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Backing Store ViewController Delegate the DataSources DataSource @[x, y, z] plist CoreData

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Delegate the DataSources

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Intentions

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Intentions UIAlertViewDelegate UITextFieldDelegate UITextFieldDelegate IBOutlets/IBActions

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Intentions Intention

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Intentions

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Intentions Michael ichael-May

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Intentions @interface ViewController () @property (strong, nonatomic) IBOutlet UILabel *translatedNameLabel; @property (strong, nonatomic) IBOutlet UITextField *nameTextField; @property (strong, nonatomic) Person *person; @end ViewController

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Intentions - (void)viewDidLoad { [super viewDidLoad]; self.person = [[Person alloc] init]; [self updateNameLabel]; } -(void)updateNameLabel { self.translatedNameLabel.text = self.person.name; } - (IBAction)convertTapped:(id)sender { self.person.name = self.nameTextField.text.pigLatinizedString; [self updateNameLabel]; } ViewController

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Intentions @interface ViewController () @property (strong, nonatomic) PersonContainer *personContainer; @end - (void)viewDidLoad { [super viewDidLoad]; Person *person = [[Person alloc] init]; self.personContainer.person = person; } ViewController.m

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Intentions @interface PigLatinIntention () @property (weak, nonatomic) IBOutlet UITextField *textField; @property (weak, nonatomic) IBOutlet UILabel *translatedNameLabel; @property (weak, nonatomic) IBOutlet PersonContainer* personContainer; @end PigLatinIntention.m

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Intentions @implementation PigLatinIntention - (IBAction)translate:(id)sender { self.personContainer.person.name = self.textField.text.pigLatinizedString; [self updateNameLabel]; } -(void)updateNameLabel { self.translatedNameLabel.text = self.personContainer.person.name; } @end PigLatinIntention.m

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Intentions

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Intentions

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Intentions

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Intentions

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Intentions

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Stores Techniques 3 Delegate(v) the DataSources Intentions

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Higher Learning Topics to Google ➡ objc.io - Lighter View Controllers

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Higher Learning Topics to Google ➡ objc.io - Lighter View Controllers ➡ Bendyworks - SRP & iOS ➡ Chris Eidhof - Intentions

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Thanks! @jaythrash [email protected] http://jaythrash.com/talks