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Swift 2.0: What's new, what's better -- interactive playground for the talk
//: Playground - noun: a place where people can play
import XCPlayground
import Foundation
import UIKit
struct UserProfile {
var username: String
var confirmed: Bool
}
//: # Error Handling
//: Defining Error Types
enum UserPermissionError: ErrorType {
case WrongPassword
case UserBanned(until: Int)
case Unconfirmed
}
//: Throwing Errors
func loadUserProfile() throws -> UserProfile {
throw UserPermissionError.WrongPassword
}
//: Basic Error Handling
do {
try loadUserProfile()
} catch UserPermissionError.WrongPassword {
print("Ooops, that has gone horribly wrong")
}
//: with Optional Values
let profile = try? loadUserProfile()
//: # Optional Checking
//: Old-fashioned way
func optionals(x: Int?) {
if x == nil || x <= 0 {
return
}
x!.description
}
optionals(nil)
optionals(0)
optionals(3)
//: Swift 1.2 style
func optionalsWithIfLet(x: Int?) {
if let x = x where x > 0 {
x.description
}
}
optionalsWithIfLet(nil)
optionalsWithIfLet(0)
optionalsWithIfLet(4)
//: Swift 2.0 style -- Guards to the rescue
func optionalsWithGuard(x: Int?) {
guard let x = x where x > 0 else {
return
}
x.description
}
optionalsWithGuard(nil)
optionalsWithGuard(0)
optionalsWithGuard(4)
//: Avoiding the pyramid of doom
//var customer = ["user": ["address" : ["country": "DE"]]]
//func parseJson(customer: [String:AnyObject]) {
// guard let user = customer["user"] else {
// return
// }
//
// guard let address = user["address"]! else {
// return
// }
//
// guard let country = address["country"]! else {
// return
// }
//
// print(country) //"DE"
//}
//: Simple Guard statement
func loadUserProfile(username: String?) -> UserProfile? {
guard let name = username where name == "Jan" else {
return nil
}
return UserProfile(username: "Jan", confirmed: true)
}
loadUserProfile("Ham")
loadUserProfile("Jan")
//: With Exceptions
//func loadUserProfile(username: String?) -> UserProfile {
// guard let name = username where name == "Jan" else {
// throw UserPermissionError.UserBanned(until: 1443778627)
// }
//
// return UserProfile(username: "Jan", confirmed: true)
//}
//
//do {
// try loadUserProfile("Ham")
//} catch let UserPermissionError.UserBanned(bannedUntil) {
// print("User is Banned until \(bannedUntil)")
//}
//
//let jan = try? loadUserProfile("Jan")
//:# Defer
func loadProfilePic() {
print("Opening File Handle")
defer { print("Close File Handle") }
print("Process File")
}
func loadAllFiles() {
print("Loading all needed files")
loadProfilePic()
print("All files loaded")
}
loadAllFiles()
//: # Protocol Extensions
//: A cross cutting concern. We want to use loggers everywhere
protocol Logger {
func log(message:String)
}
//: A basic blueprint of our "Account" domain model
protocol Account {
var firstName: String { get }
var lastName: String { get }
func fullName() -> String
}
//: Our first protocol extension
extension Logger {
func log(message:String) {
print ("log msg: \(self.dynamicType): \(message)")
}
}
//: Our first implementation of the extended protocol
struct Tweet: Logger {
var date: Int
var author: String
var text: String
func getText() -> String {
log("Having fun!")
log
return "@\(author): \(text) (send at \(date)"
}
}
let tweet = Tweet(date: 1443778627, author: "hamvocke", text: "Yo! Check out @thilo's amazing talk about protocol-oriented programming!")
tweet.getText()
//: Declaring conditions on the type for a type specific extension
extension Logger where Self: Account {
func log(message:String) -> (){
print ("nice log msg: \(NSDate()) \(self.dynamicType): \(message)")
}
}
//: A first struct which acts as a concrete implementation of our Account
struct UserAccount: Account, Logger {
var firstName: String
var lastName: String
func fullName() -> String {
log("printing my full name") //prettyLog is available here!
return "\(firstName) \(lastName)"
}
}
let account = UserAccount(firstName: "Ham", lastName: "Vocke")
account.fullName()
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