在前面一些學(xué)習(xí)中，原本把閉包給理解成了block盡管有很多相似之處，但block還是有他自己的獨(dú)特之外。近日，在寫(xiě)oc/swift混合編碼時(shí)，有時(shí)候需要swift回調(diào)oc,oc回調(diào)swift 。
因此我把swift中的 block 常見(jiàn)的聲明和寫(xiě)法作一個(gè)總結(jié)。以免后續(xù)忘了，好查閱。廢話不說(shuō)多，上例子：

//
//  blockDemo.swift
//  swiftDemo
//
//  Created by apple on 14-6-29.
//  Copyright (c) 2014年 fengsh. All rights reserved.
//
import Foundation
//無(wú)參無(wú)返回值
typealias funcBlock = () -> () //或者 () -> Void
//返回值是String
typealias funcBlockA = (Int,Int) -> String
//返回值是一個(gè)函數(shù)指針，入?yún)镾tring
typealias funcBlockB = (Int,Int) -> (String)->()
//返回值是一個(gè)函數(shù)指針，入?yún)镾tring 返回值也是String
typealias funcBlockC = (Int,Int) -> (String)->String
class blockDemo
{
    //block作為屬性變量
    var blockProperty : (Int,Int) -> String = {a,b in return ""/**/} // 帶初始化方式
    var blockPropertyNoReturn : (String) -> () = {param in }
    
    var blockPropertyA : funcBlockA?  //這寫(xiě)法就可以初始時(shí)為nil了,因?yàn)樯芷渲校?理想狀態(tài))可能為nil所以用?
    var blockPropertyB : funcBlockB!  //這寫(xiě)法也可以初始時(shí)為nil了,因?yàn)樯芷渲校?理想狀態(tài))認(rèn)為不可能為nil,所以用!
    
    init()
    {
        println("blockPropertyA = \(blockPropertyA) , blockPropertyB = \(blockPropertyB)")
        println("blockProperty = \(blockProperty) , blockPropertyNoReturn = \(blockPropertyNoReturn)")
    }
    
    func testProperty(tag:Int)
    {
        switch (tag)
        {
        case 1:
                self.blockPropertyNoReturn("OK GOOD")
        case 2:
                if let exsistBlock = self.blockPropertyA
                {
                    let result = self.blockPropertyA!(7,8)
                    println("result = \(result)")
                }
        case 3:
                if let exsistBlock = self.blockPropertyB
                {
                    let fc = self.blockPropertyB(1,2)
                    fc("輸出")
                }
        default:
                let ret = self.blockProperty(3,4)
                println(ret)
        }
    }
    
    //block作為函數(shù)參數(shù)
    func testBlock(blockfunc:funcBlock!)//使用!號(hào)不需要再解包
    {
        if let exsistblock = blockfunc
        {
            blockfunc() //無(wú)參無(wú)返回
        }
    }
    
    func testBlockA(blockfunc:funcBlockA!)
    {
        if let exsistblock = blockfunc
        {
            let retstr = blockfunc(5,6)
            println(retstr)
        }
    }
    
    func testBlockB(blockfunc:funcBlockB!)
    {
        if let exsistblock = blockfunc
        {
           let retfunc = blockfunc(5,6)
            retfunc("結(jié)果是")
        }
    }
    
    func testBlockC(blockfunc:funcBlockC!)
    {
        if let exsistblock = blockfunc
        {
            let retfunc = blockfunc(5,6)
            let str = retfunc("最終果結(jié)是")
            println(str)
        }
    }
}

執(zhí)行測(cè)試碼：

var bk = blockDemo()
//block設(shè)置前,啥也沒(méi)有輸出
bk.testProperty(0)
bk.testProperty(1)
bk.testProperty(2)
bk.testProperty(3)
println("＝＝＝＝＝＝＝＝＝＝＝＝＝＝設(shè)置block屬性＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝")

bk.blockProperty = {
    (a :Int,b:Int) -> String in
    let c = a*100+b
    return "\(a)*100+\(b) = \(c)"
}
bk.testProperty(0)

bk.blockPropertyNoReturn = {
    (param:String) -> () in
    println("input param value is : \(param)")
}
bk.testProperty(1)

bk.blockPropertyA = {
    (a:Int,b:Int) -> String in
    let c = a*100+b*200
    return "\(a)*100+\(b)*200 = \(c)"
}
bk.testProperty(2)

bk.blockPropertyB = {
    (a:Int,b:Int) -> (String)->() in
    func sumprint(result:String)
    {
        let c = a + b;
        println("sumprint func print:parame :\(result) \(a) + \(b) = \(c)")
    }
    
    return sumprint
}
bk.testProperty(3)
println("＝＝＝＝＝＝＝＝＝＝＝＝＝＝屬性block完成＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝")

println("＝＝＝＝＝＝＝＝＝＝＝＝＝＝函數(shù)block為nil時(shí)無(wú)輸出＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝")
bk.testBlock(nil)
bk.testBlockA(nil)
bk.testBlockB(nil)
bk.testBlockC(nil)
println("＝＝＝＝＝＝＝＝＝＝＝＝＝＝函數(shù)block操作＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝")
bk.testBlock({
    //do something
    println("無(wú)參無(wú)返回值block 執(zhí)行")
})

bk.testBlockA({
    (a:Int,b:Int) -> String in
    let c = a*400+b*1000
    return "\(a)*400 + \(b)*1000 is \(c)"
})

bk.testBlockB({
    (a:Int,b:Int) -> (String)->() in
    func sumprint(result:String)
    {
        let c = a / b;
        println("sumprint func print:parame :\(result) \(a) / \(b) = \(c)")
    }
    
    return sumprint
})

bk.testBlockC({
    (a:Int,b:Int) -> (String)->String in
    func sumrsult(res:String) -> String
    {
        let c = a*a+b*a
        return "\(res) \(a)*\(a)+\(b)*\(a) = \(c)"
    }
    return sumrsult
})

以上包括了block聲明和使用
下面是輸出結(jié)果

blockPropertyA = nil , blockPropertyB = nil
blockProperty = (Function) , blockPropertyNoReturn = (Function)
＝＝＝＝＝＝＝＝＝＝＝＝＝＝設(shè)置block屬性＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝
3*100+4 = 304
input param value is : OK GOOD
result = 7*100+8*200 = 2300
sumprint func print:parame :輸出 1 + 2 = 3
＝＝＝＝＝＝＝＝＝＝＝＝＝＝屬性block完成＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝
＝＝＝＝＝＝＝＝＝＝＝＝＝＝函數(shù)block為nil時(shí)無(wú)輸出＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝
＝＝＝＝＝＝＝＝＝＝＝＝＝＝函數(shù)block操作＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝
無(wú)參無(wú)返回值block 執(zhí)行
5*400 + 6*1000 is 8000
sumprint func print:parame :結(jié)果是 5 / 6 = 0
最終果結(jié)是 5*5+6*5 = 55