如何在Objective-C中声明一个Block？
接下来正文中出现词语定义:
returnType: 返回类型， NSInteger、BOOL、int、...
blockName: block名称，自己定义
parameterTypes: 参数类型 ，NSInteger、BOOL、int、...
parameters : 参数类型 +名 称 ，NSInteger index, BOOL flag ...
someObject : 对象，实例对象 、类对象、self、...
-
局部变量
returnType (^blockName)(parameterTypes) = ^returnType(parameters) {...};
NSInteger (^myblock)(BOOL) = ^NSInteger(BOOL flag) {
//code
if(flag) return 1
return 0;
};
-
属性
@property (nonatomic, copy) returnType (^blockName)(parameters);
@property (nonatomic, copy) NSInteger (^myblock)(BOOL flag);
-
方法参数
-(void)someMethodWithBlock:(returnType(^)(parameters))blockName;
- (void)someMethodWithBlock:(NSInteger(^)(BOOL flag))myblock
{
//code
NSInteger index = myblock(YES);
//处理返回值 index
}
-
方法调用的参数
[someObject someMethodWithBlock:^returnType (parameters) {...}];
[self someMethodWithBlock:^NSInteger(BOOL flag) {
///code
if (flag) return 1;
return 0;
}];
-
C函数的参数：
voidSomeFunctionWithBlock(returnType(^blockName)(parameterTypes));void someMethodWichBlock(NSInteger(^myblock)(BOOL)){ //code NSInteger index = myblock(YES); //处理返回值 index }; -
typedef：
typedef returnType (^blockName)(parameters);
blockName aBlock = ^returnType(parameters) {...};
typedef NSInteger (Myblock)(BOOL flag);
//调用
Myblock block = ^NSInteger(BOOL flag){
//code
if(flag)return 1;
return 0;
};
