**局部變量
**:

returnType (^blockName)(parameterTypes) = ^returnType(parameters) {...};


 void (^blockName)(NSInteger x) = ^void(NSInteger x){
    
    };

**聲明
**:

@property (nonatomic, copy) returnType (^blockName)(parameterTypes);

@property(nonatomic,copy)void (^textBlock)(NSInteger idx);

**方法中的參數(shù)
**:

- (void)someMethodThatTakesABlock:(returnType (^nullability)(parameterTypes))blockName;


- (void)requestForURlXXSuccess:(void(^)(NSDictionary * resultDic))sucess error:(void(^)(NSError * error))error;

**回調(diào)
**:

[someObject someMethodThatTakesABlock:^returnType (parameters) {...}];

[self requestForURlXXSuccess:^(NSDictionary *resultDic) {
        //成功
    } error:^(NSError *error) {
        //失敗
    }];
    

**typedef
**:

typedef returnType (^TypeName)(parameterTypes);TypeName blockName = ^returnType(parameters) {...};

ex:
typedef void(^TextBlock)(NSInteger x);

@interface ViewController : UIViewController

@property(nonatomic,copy)TextBlock blcok;