avaudioplayer swift tutorial

)))//llo wo 5 string concatenation Very simple answer, with a plus + or string interpolation var str1 = "hello" var str2 = "world" var str = str1 + str2 var str2 = "\(str1) hwc and the \(str2)" //hello hwc and the world 6 Case Conversion str.uppercaseString //HELLO WORLD str.lowercaseString //hello world 7 prefix suffix equals Bool Hasprefix (prefix:string) Bool Hassuffix (suffix:string) var str = "hello hwc" str.hasPrefix("hello") //true str.hasSuffix("123")

the task and execute the task. First open Xcode to build a new project, select the Swift language, then just modify the default created Viewcontroller(1) Define an abstract implementation scheme (protocol), which follows the implementation of two eventsProtocol hwcsleepdelegate{func Willstarttosleep ()func Didfinishedsleep ()}(2) Define function classes to simulate long-time tasksclass hwcsleep{ var delegate:hwcsleepdelegate?func starttosleep (time

implementationNote: Optional protocols are only valid in the @objc prefix protocol@objc indicates that the protocol is optional and that it can be exposed to objective C, and that the protocol is valid only for classesFor example@objc protocol Counterdatasource {optional Func incrementforcount (count:int), intoptional var fixedincrement:int { Get}} @objc class Counter {var count = 0var Datasource:counterdatasource?func increment () {if let amount = DataSource?. Incrementforcount? (count) {count