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Discovering Na.ve Swi1 Pa3erns
Developing clear, consise code
Nick O'Neill • @nickoneill
Discovering Na.ve Swi1 Pa3erns • June 9th, 2016
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That Thing in Swi+
let's think swi$y
Discovering Na.ve Swi1 Pa3erns • June 9th, 2016
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How can I express what I'm
doing more clearly?
Discovering Na.ve Swi1 Pa3erns • June 9th, 2016
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Sta$c table cells
Discovering Na.ve Swi1 Pa3erns • June 9th, 2016
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the objec)ve-c way
if (indexPath.section == 0) {
if (indexPath.row == 0) {
cell.textLabel.text = @"Twitter"
} else if (indexPath.row == 1) {
cell.textLabel.text = @"Blog"
} else {
cell.textLabel.text = @"Contact Us"
}
} else {
if (indexPath.row == 0) {
cell.textLabel.text = @“@nickoneill"
} else if (indexPath.row == 1) {
cell.textLabel.text = @“@objctoswift"
} else {
cell.textLabel.text = @“@whyareyousodumb"
}
}
Discovering Na.ve Swi1 Pa3erns • June 9th, 2016
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a be%er? swi+ way
let shortPath = (indexPath.section, indexPath.row)
switch shortPath {
case (0, 0):
cell.textLabel.text = "Twitter"
case (0, 1):
cell.textLabel.text = "Blog"
case (0, 2):
cell.textLabel.text = "Contact Us"
case (1, 0):
cell.textLabel.text = “@nickoneill"
case (1, 1):
cell.textLabel.text = “@objctoswift"
case (1, 2):
cell.textLabel.text = “@whyareyousodumb"
default:
cell.textLabel.text = "¯\\_(ϑ)_/¯"
}
Discovering Na.ve Swi1 Pa3erns • June 9th, 2016
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the best? swi* way
enum TwitterHandles: Int {
case Nickoneill
case Objctoswift
case Whyareyousodumb
func labelText() -> String {
switch self {
...
}
}
}
let rowData = TwitterHandles(rawValue: indexPath.row)
cell.textLabel.text = rowData.labelText()
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Our idea of the best Swi/
pa1erns will change over 8me
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Not every piece of clever code
is a great pa0ern
Discovering Na.ve Swi1 Pa3erns • June 9th, 2016
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objec&ve-c
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
// do some task
dispatch_async(dispatch_get_main_queue(), ^{
// update some UI
});
});
Discovering Na.ve Swi1 Pa3erns • June 9th, 2016
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swi$
func mainToBackground(background: () -> (), main: () -> ()) {
let priority = DISPATCH_QUEUE_PRIORITY_DEFAULT
dispatch_async(dispatch_get_global_queue(priority, 0)) {
background()
dispatch_async(dispatch_get_main_queue()) {
main()
}
}
}
mainToBackground({
// do some task
}, {
// update the ui
})
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swi$?
{ /* do some task */ } ~> { /* update some UI */}
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Great pa(erns provide convenience
while maintaining clarity
Discovering Na.ve Swi1 Pa3erns • June 9th, 2016
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Custom Operators
not even once
Discovering Na.ve Swi1 Pa3erns • June 9th, 2016
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class ViewController: UIViewController {
let imageView = UIImageView()
let goButton = UIButton()
override func viewDidLoad() {
imageView.image = UIImage(named: "profile")
view.addSubview(imageView)
goButton.frame = CGRect(x: 0, y: 0, width: 30, height: 30)
goButton.setTitle("GO!", forState: .Normal)
view.addSubview(goButton)
}
}
Discovering Na.ve Swi1 Pa3erns • June 9th, 2016
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class ViewController: UIViewController {
let imageView: UIImageView = {
let imageView = UIImageView()
imageView.image = UIImage(named: "profile")
return imageView
}()
let goButton: UIButton = {
let button = UIButton()
button.frame = CGRect(x: 0, y: 0, width: 30, height: 30)
button.setTitle("GO!", forState: .Normal)
return button
}()
override func viewDidLoad() {
view.addSubview(imageView)
view.addSubview(goButton)
}
}
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@IBOutlet weak var arrivalLabel: UILabel! {
didSet {
arrivalLabel.text = "Arriving in 10 minutes".uppercaseString
arrivalLabel.font = UIFont(name: "Lato", size: 11)
arrivalLabel.textColor = UIColor.blueColor()
arrivalLabel.textAlignment = .Center
arrivalLabel.numberOfLines = 1
}
}
Discovering Na.ve Swi1 Pa3erns • June 9th, 2016
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Swi$ pa(erns to make Swi$ be(er
Discovering Na.ve Swi1 Pa3erns • June 9th, 2016
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override func viewDidAppear(animated: Bool) {
super.viewDidAppear(animated)
if let paths = tableView.indexPathsForSelectedRows {
for path in paths {
tableView.deselectRowAtIndexPath(path, animated: true)
}
}
}
Discovering Na.ve Swi1 Pa3erns • June 9th, 2016
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tableView.indexPathsForSelectedRows?.forEach({ (path) in
tableView.deselectRowAtIndexPath(path, animated: true)
})
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tableView.indexPathsForSelectedRows?.forEach {
tableView.deselectRowAtIndexPath($0, animated: true)
}
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Simple pa)erns can replace large
dependencies
Discovering Na.ve Swi1 Pa3erns • June 9th, 2016
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Unboxing1, or any JSON -> struct framework
let json = try? NSJSONSerialization.JSONObjectWithData(data, options: [])
if let object = json as? Dictionary,
places: [Place] = Unbox(object) {
return places
}
1 h$ps:/
/github.com/JohnSundell/Unbox
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struct Place: Unboxable {
let id: String
let address: Int?
let text: String
init(unboxer: Unboxer) {
self.id = unboxer.unbox("id")
self.address = unboxer.unbox("address")
self.placeName = unboxer.unbox("place_name")
}
}
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struct Place {
// ...
init?(json: Dictionary) {
guard let id = json["_id"] as? String else {
return nil
}
self.id = id
self.address = json["address"] as? Int
self.placeName = (json["name"] as? String) ?? "No place name"
}
}
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Smart architecture decisions
are just big pa4erns
• Networking
• Core Data
• No0fica0onCenter/KVO/delegates
Discovering Na.ve Swi1 Pa3erns • June 9th, 2016
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Tips for finding new pa0erns
• Develop an intui.on for code smell
• Experiment in playgrounds or simplified projects
• Re-read the language guide
• Keep things clear
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Thanks!
Ques%ons? Comments?
@nickoneill • [email protected]
Discovering Na.ve Swi1 Pa3erns • June 9th, 2016