Swift4 闭包小结

//: Playground - noun: a place where people can play

//Swift 闭包
//定义
//无参数无返回值的闭包
var completionCallback :(()->())?
//无参数有返回值的闭包
var completionHandler:(()->Int)?
//有参数无返回值的闭包
var finishCallBack :((Int) ->())?
//有参数有返回值的闭包
var successHandler :((Int) ->(Int))?

//无参数无返回值的闭包
completionCallback = { () in
    print("无参数无返回值的闭包执行了");
};

completionCallback!();

//无参数有返回值的闭包
completionHandler = { ()in
    print("闭包被调用了");
    return 20;
};
let a = completionHandler!();
print(" a:\(a)")

//有参数无返回值的闭包
finishCallBack = { (a) in
    print("有参数无返回值的闭包 a:\(a)")
};

finishCallBack!(10);

//有参数有返回值的闭包
successHandler = {(a) ->(Int)in
    print("有参数有返回值 a:\(a)");
    return 10;
};

let result = successHandler!(20);
print(result);

// 闭包作为参数传递的情况
func successFunction(success:@escaping (Int)->(Int)) -> () {
    
    successHandler = success;
    
    let result = success(10);
    
    print("successFunction result :::\(result)")
    
}


func doSomthing(finish:@escaping (Int)->()) -> () {
    
    finishCallBack = finish;
    
    finish(10);
    
    
}

func loadNetWorkData(completion:@escaping ()->Int) -> () {
    
    completionHandler = completion;
    
    let a = completion();
    
    print("a:\(a)");
    
    
}