Swifter Tips - 2 - Notes: http://www.jianshu.com/p/85dbf5a524e8

01.实例方法的动态调用.swift

import UIKit

// 通过类型取出某个实例方法的签名，再传入实例调用相应的方法
class ClassA {
    func method(_ number: Int) -> Int {
        return number + 1
    }
}

// func1: (ClassA) -> (Int) -> Int
let func1 = ClassA.method
// let func1 = { (obj: MyClass) in obj.method }
let obj1 = ClassA()
let rst1 = func1(obj1)(1)
print(rst1)
// OUTPUT:
// 2

class ClassB {
    func method(_ number: Int) -> Int {
        return number + 1
    }
    
    class func method(_ number: Int) -> Int {
        return number
    }
}

// func2: (Int) -> Int
let func2 = ClassB.method
let func3: (Int) -> Int = ClassB.method
let func4: (ClassB) -> (Int) -> Int = ClassB.method
print(func2(1))
print(func3(1))

let obj2 = ClassB()
print(func4(obj2)(1))
// OUTPUT:
// 1
// 1
// 2

02.可选协议和协议扩展.swift

import UIKit

@objc protocol OptionalProtocol {
    @objc optional func optionalMethod()
    func necessaryMethod()
}

protocol SwiftProtocol {
    func methodOpA()
    func methodNsB()
    func methodOpC()
}

extension SwiftProtocol {
    func methodOpA() {
        print(#function)
    }
    
    func methodOpC() {
        print(#function)
    }
}

class ClassA: SwiftProtocol {
    func methodOpA() {
        print(#function)
    }
    
    func methodNsB() {
        print(#function)
    }
}

class ClassB: OptionalProtocol {
    func necessaryMethod() {
        print(#function)
    }
}

03.UnsafePointer.swift

import UIKit

func method(_ num: UnsafePointer<CInt>) {
    print(num.pointee)
}

func method(_ num: UnsafeMutablePointer<CDouble>) {
    num.pointee = 1.5
    print(num.pointee)
}

var a: CInt = 123
method(&a)

var b: CDouble = 3.14
method(&b)

// 指针内容和实际值转换 - 不安全
let arr = NSArray(object: "meow")
let str = unsafeBitCast(CFArrayGetValueAtIndex(arr, 0), to: CFString.self)

04.C指针内存管理.swift

import UIKit

class MyClass {
    var a = 1
    deinit {
        print(#function)
    }
}

var pointer: UnsafeMutablePointer<MyClass>!
pointer = UnsafeMutablePointer<MyClass>.allocate(capacity: 1)
pointer.initialize(to: MyClass())
print(pointer.pointee.a)

pointer.deinitialize()
pointer.deallocate(capacity: 1)
pointer = nil
// OUTPUT:
// 1
// deinit

var x: UnsafeMutablePointer<tm>!
var t = time_t()
time(&t)
x = localtime(&t)
x = nil

05.获取对象类型.swift

import UIKit

let date = NSDate()
let name: AnyClass! = object_getClass(date)
print(name)

let type = type(of: date)
print(type)
// OUTPUT:
// __NSDate
// __NSDate

06.自省.swift

import UIKit

class ClassA: NSObject {}
class ClassB: ClassA {}

let obj1: NSObject = ClassA()
let obj2: NSObject = ClassB()

obj1.isKind(of: ClassA.self)
obj2.isMember(of: ClassA.self)

class ClassC {}
class ClassD: ClassC {}

let obj3: AnyObject = ClassC()
let obj4: AnyObject = ClassD()

obj3.isKind(of: ClassC.self)
obj4.isMember(of: ClassC.self)

if obj4 is ClassC {
    print("obj4 is ClassC")
}

if obj4 is ClassD {
    print("obj4 is ClassD")
}
// OUTPUT:
// obj4 is ClassC
// obj4 is ClassD

// Warning
//let str = ""
//if str is String {
//    print("str is a string.")
//}

07.KVO.swift

import Foundation

typealias Task = (_ cancel: Bool) -> Void

func delay(_ time: TimeInterval, task: @escaping () -> ()) -> Task? {
    func dispatch_later(block: @escaping () -> ()) {
        let t = DispatchTime.now() + time
        DispatchQueue.main.asyncAfter(deadline: t, execute: block)
    }
    
    var closure: (() -> Void)? = task
    var result: Task?
    
    let delayedClosure: Task = { cancel in
        if let internalClosure = closure {
            DispatchQueue.main.async(execute: internalClosure)
        }
        
        closure = nil
        result = nil
    }
    
    result = delayedClosure
    
    dispatch_later {
        if let delayedClosure = result {
            delayedClosure(false)
        }
    }
    
    return result
}

class ClassA: NSObject {
    dynamic var date = Date()
}

private var myContext = 0

class ClassB: NSObject {
    var obj: ClassA!
    
    override init() {
        super.init()
        
        obj = ClassA()
        print("Init ClassA - Date: \(obj.date)")
        
        obj.addObserver(self,
                        forKeyPath: "date",
                        options: .new,
                        context: &myContext)
        
        _ = delay(3) {
            self.obj.date = Date()
        }
    }
    
    override func observeValue(forKeyPath keyPath: String?, of object: Any?, change: [NSKeyValueChangeKey : Any]?, context: UnsafeMutableRawPointer?) {
        if let change = change, context == &myContext {
            let newDate = change[.newKey]
            print("Date changed - New Date: \(newDate ?? "nil")")
        }
    }
}

let obj = ClassB()

08.局部scope.swift

import UIKit

func local(_ closure: () -> ()) {
    closure()
}

local {
    // Code goes here...
}

local {
    // Code goes here...
}

do {
    // Code goes here...
}

do {
    // Code goes here...
}

let sth: UILabel = {
    let label = UILabel()
    // Setup label...
    return label
}()

09.类簇.swift

import UIKit

class Drinking {
    typealias LiquidColor = UIColor
    
    var color: LiquidColor {
        return .clear
    }
    
    class func drinking(_ name: String) -> Drinking {
        var drinking: Drinking
        
        switch name {
        case "Coke":
            drinking = Coke()
        case "Beer":
            drinking = Beer()
        default:
            drinking = Drinking()
        }
        
        return drinking
    }
}

class Coke: Drinking {
    override var color: LiquidColor {
        return .black
    }
}

class Beer: Drinking {
    override var color: LiquidColor {
        return .yellow
    }
}

let coke = Drinking.drinking("Coke")
coke.color

let beer = Drinking.drinking("Beer")
beer.color

print(NSStringFromClass(type(of: coke)))
print(NSStringFromClass(type(of: beer)))
// OUTPUT:
// __lldb_expr_5.Coke
// __lldb_expr_5.Beer

10.调用C动态库.swift

// Demo-Bridging-Header.h
// #import <CommonCrypto/CommonCrypto.h>

// Swift
extension String {
    var MD5: String {
        var digest = Array<UInt8>(repeating: 0, count: Int(CC_MD5_DIGEST_LENGTH))
        if let data = data(using: .utf8) {
            data.withUnsafeBytes({ (bytes: UnsafePointer<UInt8>) -> Void in
                CC_MD5(bytes, CC_LONG(data.count), &digest)
            })
        }
        
        var digestHex = ""
        for index in 0..<Int(CC_MD5_DIGEST_LENGTH) {
            digestHex += String(format: "%02x", digest[index])
        }
        return digestHex
    }
}

print("maimieng.com".MD5)
// OUTPUT:
// abd67f15825d199d8fe203e751647f64

11.OptionSet.swift

import UIKit

struct MyOption: OptionSet {
    let rawValue: UInt
    
    static let none = MyOption(rawValue: 0)
    static let option1 = MyOption(rawValue: 1)
    static let option2 = MyOption(rawValue: 1 << 1)
}

12.类型编码.swift

import UIKit

let int: Int = 0
let float: Float = 0.0
let double: Double = 0.0

let intNumber: NSNumber = int as NSNumber
let floatNumber: NSNumber = float as NSNumber
let doubleNumber: NSNumber = double as NSNumber

print(String(validatingUTF8: intNumber.objCType))
print(String(validatingUTF8: floatNumber.objCType))
print(String(validatingUTF8: doubleNumber.objCType))

let p = NSValue(cgPoint: CGPoint(x: 3.0, y: 3.0))
print(String(validatingUTF8: p.objCType))

let t = NSValue(cgAffineTransform: .identity)
print(String(validatingUTF8: t.objCType))
// OUTPUT:
// Optional("q")
// Optional("f")
// Optional("d")
// Optional("{CGPoint=dd}")
// Optional("{CGAffineTransform=dddddd}")

13.C代码调用和@_silgen_name.swift

// C
// int test(int a) {
//     return a + 1;
// }

import UIKit

@_silgen_name("test") func c_test(_ a: Int32) -> Int32

print(c_test(99))
// OUTPUT:
// 100

14.AssociatedObject.swift

class Class {}

private var key: Void?

extension Class {
    var title: String? {
        get {
            return objc_getAssociatedObject(self, &key) as? String
        }
        
        set {
            objc_setAssociatedObject(self,
                                     &key,
                                     newValue,
                                     .OBJC_ASSOCIATION_COPY_NONATOMIC)
        }
    }
}

let a = Class()
a.title = "maimieng.com"
print(a.title ?? "nil")
// OUTPUT:
// maimieng.com

15.Lock.swift

func myMethodLock(_ obj: AnyObject!) {
    func synchronized(_ lock: AnyObject!, closure: () -> ()) {
        objc_sync_enter(lock)
        closure()
        objc_sync_exit(lock)
    }
    
    synchronized(obj) { 
       // do sth...
    }
}