Note: More Swift and Foundation Frameworks

Intro

Note of More Swift and Foundation Frameworks, not detail described.
Lesson4的要点记录，有些没有展开，侧重于“点”。看完后觉得需要注意的地方：基本数据类型如Optional/Array/Dictionary等的特点；class与struct的异同；class中的属性和方法；常见数据类型的常用方法(Array/String有很多新增的方法，功能比对应的ObjC强大)

Optional

an optional is an enum
enum Optional
{
case None
case Some(T)
}

! 相当于一个switch
简单的说，就是语法糖

Array

declare
immutable
enumerating

Dictionary

like above
enumerating using tuple

Range

it’s new
Array’s range :Range<Int>
String’s : Range<String.Index>
… / ..< (close/open)
enumerating
for i in [start…end]{}

Other class

NSObject

advanced features require subclass from NSObject

NSNumber

inherited from NSObject
–bridged–

NSDate

NSData

Data structure in swift

这个重要
class/struct/enum : 3 fundamental building blocks of data structure
Similariries:
1. declaration
2. oproperty and functions
3. initializer
Differences:
1. Inheritance
2. Introspection and casting
3. value type vs. Reference type

Value VS. References

Value

copied && immutable && mutating

Reference

heap && reference counted

Choose

Methods

override &&final(can be class)
types and instances can have methods/properties: (like class and instance methods)

static func abc(d: Double) -> Double
class func abc(d: Double) -> Double

Parameters Names * internal: local var used in method * external: caller used to call method

func foo (external internal :Int)
{
    let local = internal
}
fun bar ()
{
    let result = foo(external :123)
}

But we seldomly write like above.

  • _ : means not use an external name, default

    func foo ( internal :Int)// can be omitted
    {
    let local = internal
    }
    fun bar ()
    {
    let result = foo(123)
    }

  • #: force the 1st parameter’s external name to be the internal one

    func foo (#internal :Int)
    {
    let local = internal
    }
    fun bar ()
    {
    let result = foo(internal :123)
    }

  • not 1st parameter: external is the internal by default; but can be changed

    //1
    func foo (first :Int, second: Doube)
    {
    let local = internal
    }
    fun bar ()
    {
    let result = foo(123, second: 5.5)
    }
    //2
    func foo (first :Int, external2nd second: Doube)
    {
    let local = internal
    }
    fun bar ()
    {
    let result = foo(123, external2nd: 5.5)
    }
    //3 also can be ommited, not recommended to to do
    func foo (first :Int, _ second: Doube)
    {
    let local = internal
    }
    fun bar ()
    {
    let result = foo(123, 5.5)
    }

使用默认的即可，其他的需要知道这种语法，遇到的时候能认识就行

Property

observer

类似KVO
willset didset

var someProperty: Int = 42 {
    willSet { newValue}
    didSet { oldValue}
}
override var inheriteProperty
{
    willSet { newValue }
    didSet { oldValue}
}

Lazy Initialization

like dynamic, when in use to access, the var is initialized

lazy var brain = ...

can’t use let together
may have dependence problems (dependency conundrums)

Initialization

  • when is init method needed: usually not
  • free init : base class have defaults/struct automaticalled created
  • what can to do in init: set any property’s value even those have defaults; constant value;self.init();super.init()
  • what required in init: all properties must have values; convenience and designated(not convience); desigated can only call a init of its superclass; must init own property before call super.init; must call super.init before assign the inherited value; convenience can only call a designated init in its own and may call desiganated init directly; must call init before set property;
    all in all: init is requred before any setting

Inhering init

Required init

Failable init

init?()
{
    // may return nil
}

Createing Objects

Any Object

Special type: a protocol

var viewController : AnyObject
var items :[AnyObject]

like id, Not common use in swift and convert it before using
Casting: as/ as ?

//1
if let viewController = someController as? CalViewController {}// as? returns an optional
//2
if someController is CalViewController {...}

Functions

some Array Methods

+= [T]
first -> T
last -> T
append
slice
insert
remove Index/Range
sort
filter
map 
reduce

String

String.Index

is NOT Int

//1
var s = "hello"
let index = advance(s.startIndex, 2)// a String.Index to 3rd glyph, "l"
s.splice("abc",index)// s= "heabcllo"
//2
let num = "56.25"
if let decimalRange = num.rangeOfString(".")
{
    let wholeNumberPart = num[num.startIndex..<decimalRange.startindex]
}

Other methods
Notice : NO toDouble

Type Conversion

//1
let d: Double = 37.5
let f: Float = 37.5
let x = Int(d)
let cd = Double(x)
//2: notice here
let a = Array("abc")// a = ["a","b","c"]
let s = String("a","b","c"]) //s = "abc"

Assertions

Debugging Aid

Other Functions

Bridging

Comments

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