iOS 入门常见问题

1. Device os version lower than deployment target

我把手机连接电脑后,准备跑项目,但是Xcode提醒Device os version lower than deployment target

原因是项目要求最低版本高于手机版本,单击项目修改Deployment Target即可

APIhttps://developer.apple.com/library/ios/navigation/

学习视频http://open.163.com/special/opencourse/ios8.html

/Users/maizhikun/Learning/iOS/workspace/Calculatoer/Calculatoer/CalculatorBrain.swift:12:22: ‘Printable’ has been renamed to ‘CustomStringConvertible’

enum Op: Printable改成

enum Op: CustomStringConvertible

书籍

http://www.zhihu.com/question/24004342

学习博客

http://blog.csdn.net/Yt7589#rd?sukey=fc78a68049a14bb282a9238cb43355c93c53ed2c5959342e3c9a2d814b2888b1f46e19db83593016565093d093f7aff4

白胡子教程笔记

第四课Swift和Foundation框架

  1. 数组

     var a = Arry<String>()

 var a = [String]()

 var animals = ["Giraffe","Cow"]

 animals.append("Dog");

 let animal = animals[1]

 for animals in animals {
     println("\(animal)")
 }

  2. Dictonary

     var pac10teamRankings = Dictionary<String, Int>()

 var pac10teamRankings = [String:Int]()

 pac10teamRankings = ["Stanford":1,"Cal":10]

 let ranking = pac10teamRankings["Ohin State"] //return nil

 for (key , value ) in pack10teamRankings {
     println("\(key) = \(value)")
 }

  3. Rabge

     struct Range<T>{
     var startIndex :T
     var endIndex: T
 }

    An Array’s range would be a Range

    Warning: A String subrange is not Range(it is Range<String.Index> … we’ll talk later!)

    There is special syntax for specifying a Range: either …(ubclusive) or ..<(open-ended)

     let array =["a","b","c","d"]

 let subArray1 = array[2...3] //return ["c","d"]

 let subArray2 = array[2..<3] // return ["c"]

 for i in [27...104]{
 }

  4. 其他数据类型

     NSObject
 NSNumber
 NSDate
 NSData

  5. 数据类型

     //声明
 class CalculatorBrain { }

 struct Vertex  {}

 enum Op {}

 //函数

 func doit(argument: Type) -> ReturnValue{}

 var storedProperty =<initial value>(not enum)

 var computerProperty: Type{
     get {}
     set {}
 }

 //构造函数
 init(argument1: Type, argument2: Typ2, ...){}
    三者不同点:
    1. Inheritance(class only)
    2. Introspection and castring(class only)
    3. Value type(struct,enum) vs. Referenct type(class)

  6. Value vs. Referenct

    Value:

    You must note any func that can mutate a struct/enum with the keyword mutaint

    Referenct :

  7. Methods

    重写父类方法/属性时,要使用override

    final 标记不能被重写的方法和属性

     var d: Double =...

 if d.isSignMinus {
     d =Double.abs(d)
 }

 static func abs(d: Double) -> Double{}


 //Parameter Names 
 1.
 func foo(external internal: Int){
     let local = internal
 }

 func bar() {
     let result = foo(external: 123)
 }

 2.我部想拥有一个外部名
 func foo(_ internal: Int){
     let local = internal
 }

 func bar(){
     let result = foo(123)
 }

 3. 必须要外部名
 func foo(#internal: Int){
     let local = internal
 }

 func bar(){
     let result = foo(internal: 123)
 }

 4.
 func foo(first: Int, second: Double){
     let local =internal
 }

 func bar(){
     let result = foo(123, second 5.5)
 }

 5. 
 fimc fpp(first: Int, externalSecond second: Double){
     let local =internal //?这是不是错了?
 }

 func bar(){
     let result = foo(123, externalSecond: 5.5)
 }

 6. 
 func foo(first: Int, _ second: Double){
     let local = internal 
 }

 func bar(){
     let result =foo(123,5.5)
 }

  8. Properties

     var someStoredProperty: Int =42{
     willset { newValue is the new value }
     didSet {oldValue is the old value }
 }

  var inheritedProperty {
     willSet { newValue is the new value}
     didSet { oldValue is the old value}
 }

    Lazy Initialization (惰性实例化)

    只有var 可以用lazy ,let不可以

     lazy var brain = Calculator Brain()

 lazy var someProperty: Type =  {
     return <the constructed value >
 }

 lazy var myProperty =self.initializeMyProperty()

  9. Initialization

    lazy 或者其他很多方法可以避免initiative

     selfinit(<args>)

 super.init(<args>)
    两种构造方法 
     1. Convenience Init
     1. 只能调用本类的designated initializer
     2. 只能通过本类的designated intializer才能访问其他的值
 2. Designated Initalizers(default)
     1. 之前不能有Convenience Init
     2. 只能调用其父类的Designated initializer
     3. 调用父类的Init前,先初始化所有的property
     4. 必须先让父类初始化property才能给子类调用

    子类没写designated init则继承父类所有的designated init和Converienct init,否则不继承父类的所有designated init

    required init 子类必须实现这个方法

     init?(arg1: Type1, ...){}

 let image = UIImage(named: "foo")

 if let image = UIImage(named: "foo"){
     successfully 
 }else {
     faled
 }

 let commaSeparatedArrayElements: String = ",".join(myArray)

  10. AnyObject

    主要用来兼用现有的Object-C和iOS代码

    var destinationViewController: AnyObject
var toolbarItems: [AndObject]

func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject)
func appConstraints(constraints: [AnyObject])
func appendDigit(sender: AnyObject)

class func buttonWithType(buttonType: UIButtonType) -> AnyObject

let calcVC = destinationViewController as CalculatorViewController 

if let calcVC = destinationViewController as? CalculatorViewController {...}

---

var toolbarItems: [AnyObject]

for item in toolbarItems {
    if let toolbarItem = item as? UIBarButtonItem{

    }
}

for toolbarItem in toolbarItems as [UIBarButtonItem] {
    //不能使用as? 因为for toolbarItem in nil是无意义的
}

---

let button: AnyObject =UIButton.buttonWithType(UIButtonType.System)

let tutle = (button as UIButton).currentTitle

11 Function

//Some Array<T> Methods
+=[T] //not +=T 

var a = [a,b,c]

append(T)

insert(T, atIndex : Int)

splice(Array<T>,atIndex: Int)   a.splice([d,e], atIndex:1),a = [a,d,e,b,c]

removeAtIndex(Int)

removeRange(Range) a.removeRange(0..<2) a = [c]

replaceRange(Range, [T]) //a.replaceRange(0...1 with: [x,y,z]),a= [x,y,z,b]

sort(isOrderedBefore : (T,T)) -> Bool) //e.g a.sort($$0 <$1)

filter(includeElement: (T) -> Bool) -> [T]

let stringified: [String] = [1,2,3].map{ "\($0)"}

let sum: Int = [1,2,3].reduce(0) {$0 + $1}

//String

var s = "hello"

let index = advance(s.startIndex,2) //return  l

s.splice("abc",index) // return heabcllo

let startIndex =advance(s.startIndex,1)

let endIndex = advance(s.startIndex,6)

let substring = s[index..<endIndex] // return eabcl

//String.Index

let num = "56.25"

if let decimalRange = num.rangeOfString("."){
    let wholeNumberPart = num[num.startIndex..<decimalRange.startIndex]
}

s.removeRange([s.startIndex..<decimalRange.startIndex])

//Other String Methods

description ->String //Printable

endIndex -> String.Index

hasPrefix(String)) -> Bool

hasSuffix(String) -> Bool

toInt -> Int?  //not toDouble

capitalizedString -> String 

lowercaseString -> String

uppercaseString -> String 

join(Array) -> String // ",".join(]"1","2",3""]) = "1,2,3"

componentsSeparatedByString(Strign ) -> [String] // "1,2,3".csbs(",") = ["1","2","3"]

//Type Conversion

let d: Double =37.5

let f: Falot = 37.5

let x = Int(d)

let xd = Double(x)

let cgf =CgFloat(d)

let a = Array("abc")  // a = ["a","b","c"]

let s = String(["a","b","c"]) // return s = "abc"

let s = String(52)

let s= "\(37.5)"

//Assertions 

assert(() -> Bpp; ,"message")

e.g: assert(validation() !=nil,"the validation function returned nil")

//Other Functions 

let count = countElements(aCollection) //how many elements in the collection

let sub = dropFirst(aSliceable) //drops the first thing in the sliceable

let sub dropLast(aSliceable) // drops the last thing in the sliceable

let first = first(aCollection) 

let last = last(aCollection)

let prefix = prefix(aSliceable, X:Int)

let suffix = suffix(aSliceable, X: Int)

let reversed: Array = reverse(aCollection)

let backwardsSTRING = String(reverse(s))
ios

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