//1.使用typedef定义一个block
typedef void(^CallBack1)(); //不带参数 
typedef void(^CallBack2)(NSString *test); //带参数
//2.通过属性声明
@property (nonatomic, copy) CallBack callBack;
//3.通过函数方法声明
- (void)functionCallBack:(CallBack)callBack;

@property (nonatomic, strong) void(^ completed1)();//不带参数
@property (nonatomic, strong) void(^ completed2)(NSString *test);//带参数
- (void) functionCallBack:(void(^)())completed1;//不带参数
- (void) functionCallBack:(void(^)(NSString *test))completed2;//带参数

//1.使用typealias定义
typealias functionBlock1 = () -> ()//不带参数
typealias functionBlock2 = (String) -> ()//带参数
//2.声明函数体
func blockTest1(complete: (functionBlock1)) -> () {
  complete()
}
func blockTest2(complete: (functionBlock2)) -> () {
  let re: String = "Cookie"
  complete(re)
}
//3.使用函数
blockTest1 {}
blockTest2{ (result) in
   print(result)
}

//1.声明函数体
func blockTest(complete: (_ result: String)->()) -> () {
  
  let re: String = "Cookie"
  complete(re)
}
//2.使用函数
blockTest { (result) in
   
   print(result)
}