不使用 typedef 声明块方法参数

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最佳答案

- ( void )myMethodTakingPredicate: ( BOOL ( ^ )( int ) )predicate

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事情就是这样的，比如说..。

[self smartBlocks:@"Pen" youSmart:^(NSString *response) {
NSLog(@"Response:%@", response);
}];




- (void)smartBlocks:(NSString *)yo youSmart:(void (^) (NSString *response))handler {
if ([yo compare:@"Pen"] == NSOrderedSame) {
handler(@"Ink");
}
if ([yo compare:@"Pencil"] == NSOrderedSame) {
handler(@"led");
}
}

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另一个例子(这个问题受益于多个) :

@implementation CallbackAsyncClass {
void (^_loginCallback) (NSDictionary *response);
}
// …




- (void)loginWithCallback:(void (^) (NSDictionary *response))handler {
// Do something async / call URL
_loginCallback = Block_copy(handler);
// response will come to the following method (how is left to the reader) …
}


- (void)parseLoginResponse {
// Receive and parse response, then make callback


_loginCallback(response);
Block_release(_loginCallback);
_loginCallback = nil;
}




// this is how we make the call:
[instanceOfCallbackAsyncClass loginWithCallback:^(NSDictionary *response) {
// respond to result
}];

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Http://fuckingblocksyntax.com

作为方法参数:

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

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更清楚了！

[self sumOfX:5 withY:6 willGiveYou:^(NSInteger sum) {
NSLog(@"Sum would be %d", sum);
}];


- (void) sumOfX:(NSInteger)x withY:(NSInteger)y willGiveYou:(void (^) (NSInteger sum)) handler {
handler((x + y));
}