swift中的block回调
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- //
- // blockDemo.swift
- // swiftDemo
- //
- // Created by apple on 14-6-29.
- // Copyright (c) 2014年 fengsh. All rights reserved.
- //
- import Foundation
- //无参无返回值
- typealias funcBlock = () -> () //或者 () -> Void
- //返回值是String
- typealias funcBlockA = (Int,Int) -> String
- //返回值是一个函数指针,入参为String
- typealias funcBlockB = (Int,Int) -> (String)->()
- //返回值是一个函数指针,入参为String 返回值也是String
- typealias funcBlockC = (Int,Int) -> (String)->String
- class blockDemo
- {
- //block作为属性变量
- var blockProperty : (Int,Int) -> String = {a,b in return ""/**/} // 带初始化方式
- var blockPropertyNoReturn : (String) -> () = {param in }
- var blockPropertyA : 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?
- var blockPropertyB : 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)")
- }
- 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("输出")
- }
- default:
- let ret = self.blockProperty(3,4)
- println(ret)
- }
- }
- //block作为函数参数
- func testBlock(blockfunc:funcBlock!)//使用!号不需要再解包
- {
- if let exsistblock = blockfunc
- {
- blockfunc() //无参无返回
- }
- }
- 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("结果是")
- }
- }
- func testBlockC(blockfunc:funcBlockC!)
- {
- if let exsistblock = blockfunc
- {
- let retfunc = blockfunc(5,6)
- let str = retfunc("最终果结是")
- println(str)
- }
- }
- }
执行测试码:以上包括了block声明和使用- var bk = blockDemo()
- //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) -> 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("==============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({
- //do something
- println("无参无返回值block 执行")
- })
- 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
- })
下面是输出结果- blockPropertyA = nil , blockPropertyB = nil
- blockProperty = (Function) , blockPropertyNoReturn = (Function)
- ==============设置block属性================
- 3*100+4 = 304
- input param value is : OK GOOD
- result = 7*100+8*200 = 2300
- sumprint func print: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*1000 is 8000
- sumprint func print:parame :结果是 5 / 6 = 0
- 最终果结是 5*5+6*5 = 55
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