作者:fengsh998
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原文地址:http://blog.csdn.net/fengsh998/article/details/35783341
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在前面一些学习中,原本把闭包给理解成了block尽管有很多相似之处,但block还是有他自己的独特之外。近日,在写oc/swift混合编码时,有时候需要swift回调oc,oc回调swift 。
因此我把swift中的 block 常见的声明和写法作一个总结。以免后续忘了,好查阅。废话不说多,上例子:
[cpp]
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- //
- //blockDemo.swift
- //swiftDemo
- //
- //Createdbyappleon14-6-29.
- //Copyright(c)2014年fengsh.Allrightsreserved.
- importFoundation
- //无参无返回值
- typealiasfuncBlock=()->()//或者()->Void
- //返回值是String
- typealiasfuncBlockA=(Int,Int)->String
- //返回值是一个函数指针,入参为String
- typealiasfuncBlockB=(Int,Int)->(String)->()
- //返回值是一个函数指针,入参为String返回值也是String
- typealiasfuncBlockC=(Int,Int)->(String)->String
- classblockDemo
- {
- //block作为属性变量
- varblockProperty:(Int,Int)->String={a,binreturn""/**/}//带初始化方式
- varblockPropertyNoReturn:(String)->()={paramin}
- varblockPropertyA:funcBlockA?//这写法就可以初始时为nil了,因为生命周其中,(理想状态)可能为nil所以用?
- varblockPropertyB:funcBlockB!//这写法也可以初始时为nil了,因为生命周其中,(理想状态)认为不可能为nil,所以用!
- init()
- {
- println("blockPropertyA=\(blockPropertyA),blockPropertyB=\(blockPropertyB)")
- println("blockProperty=\(blockProperty),blockPropertyNoReturn=\(blockPropertyNoReturn)")
- }
- functestProperty(tag:Int)
- switch(tag)
- case1:
- self.blockPropertyNoReturn("OKGOOD")
- case2:
- ifletexsistBlock=self.blockPropertyA
- letresult=self.blockPropertyA!(7,8)
- println("result=\(result)")
- }
- case3:
- ifletexsistBlock=self.blockPropertyB
- letfc=self.blockPropertyB(1,2)
- fc("输出")
- default:
- letret=self.blockProperty(3,4)
- println(ret)
- //block作为函数参数
- functestBlock(blockfunc:funcBlock!)//使用!号不需要再解包
- ifletexsistblock=blockfunc
- blockfunc()//无参无返回
- functestBlockA(blockfunc:funcBlockA!)
- letretstr=blockfunc(5,6)
- println(retstr)
- functestBlockB(blockfunc:funcBlockB!)
- ifletexsistblock=blockfunc
- letretfunc=blockfunc(5,6)
- retfunc("结果是")
- functestBlockC(blockfunc:funcBlockC!)
- letretfunc=blockfunc(5,108); list-style:decimal-leading-zero outside; color:inherit; line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important"> letstr=retfunc("最终果结是")
- println(str)
- } @H_643_404@ @H_403_3@
- //block设置前,啥也没有输出
- bk.testProperty(0)
- bk.testProperty(1)
- bk.testProperty(2)
- bk.testProperty(3)
- println("==============设置block属性================")
- bk.blockProperty={
- (a:Int,b:Int)->Stringin
- letc=a*100+b
- return"\(a)*100+\(b)=\(c)"
- bk.testProperty(0)
- bk.blockPropertyNoReturn={
- (param:String)->()in
- println("inputparamvalueis:\(param)")
- bk.blockPropertyA={
- (a:Int,b:Int)->Stringin
- letc=a*100+b*200
- return"\(a)*100+\(b)*200=\(c)"
- bk.blockPropertyB={
- funcsumprint(result:String)
- letc=a+b;
- println("sumprintfuncprint:parame:\(result)\(a)+\(b)=\(c)")
- returnsumprint
- bk.testProperty(3)
- println("==============属性block完成================")
- println("==============函数block为nil时无输出================")
- bk.testBlock(nil)
- bk.testBlockA(nil)
- bk.testBlockB(nil)
- bk.testBlockC(nil)
- println("==============函数block操作================")
- bk.testBlock({
- //dosomething
- println("无参无返回值block执行")
- })
- bk.testBlockA({
- letc=a*400+b*1000
- return"\(a)*400+\(b)*1000is\(c)"
- bk.testBlockB({
- letc=a/b;
- println("sumprintfuncprint:parame:\(result)\(a)/\(b)=\(c)")
- })
- bk.testBlockC({
- funcsumrsult(res:String)->String
- letc=a*a+b*a
- return"\(res)\(a)*\(a)+\(b)*\(a)=\(c)"
- returnsumrsult
- }) @H_643_404@ @H_403_3@ 以上包括了block声明和使用
- blockProperty=(Function),blockPropertyNoReturn=(Function)
- ==============设置block属性================
- 3*100+4=304
- inputparamvalueis:OKGOOD
- result=7*100+8*200=2300
- sumprintfuncprint:parame:输出1+2=3
- ==============属性block完成================
- ==============函数block为nil时无输出================
- ==============函数block操作================
- 无参无返回值block执行
- 5*400+6*1000is8000
- sumprintfuncprint:parame:结果是5/6=0
- 最终果结是5*5+6*5=55 @H_643_404@ @H_403_3@
执行测试码:
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- varbk=blockDemo()
下面是输出结果
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- blockPropertyA=nil,blockPropertyB=nil