ios - 从 block 内回调 block

Question

我想我正在经历一个脑雾日……但是有可能从一个 block 内传回一个 block 吗？

例如:

typedef void(^SomeBlock)(int someValue);
typedef void(^SomeOtherBlock)(int someOtherValue, SomeBlock originalBlock); // how would you pass SomeBlock?


- (void)getSomeValue:(SomeOtherBlock)completionBlock {
  [self someMethod:^(int someValue){
    // How could I call SomeOtherBlock & pass back SomeBlock?
    int someOtherValue = 2;
    // I.e, completionBlock(someOtherValue, SomeBlock);
  }];
}
- (void)someMethod:(SomeBlock)completionBlock {
  completionBlock(1);
}

这是我得到的，但它看起来真的很丑:

- (void)getSomeValue:(SomeOtherBlock)completionBlock {
  [self someMethod:^(int someValue) {
    int someOtherValue = 2;
    SomeBlock someBlock = ^(int innerVal) {
      innerVal = someValue;
    };
    completionBlock(someOtherValue, someBlock);
  }];
}
- (void)someMethod:(SomeBlock)completionBlock {
  completionBlock(1);
}

简而言之，目标是执行第一个 block 并分析来自该 block 的回调。然后，将第一个 block 作为参数传递给第二个 block 。

Answer 1

问题的答案非常直截了当，但我怀疑这不是您真正的问题。您的问题中没有任何内容表明异步行为，但您一直在说“完成 block ”。从非异步 block 中获取结果只是返回结果的问题:

// SomeBlock takes an int and returns an int
// (In your example you have it return void, but then what is "analyzed?"
typedef int(^SomeBlock)(int someValue);

// SomeOtherBlock takes an int and also a SomeBlock
typedef void(^SomeOtherBlock)(int someOtherValue, SomeBlock originalBlock);


void executeAnalyzeAndContinue(SomeBlock firstBlock, SomeOtherBlock secondBlock, int value) {
    // execute the first block
    int result = firstBlock(value);

    // and analyze the callback (return value?) from that block. 
    if (result == 2) { NSLog(@"%@", @"It was two"); }

    // Then, pass the first block as a parameter to the second block (and also a value?)
    secondBlock(result, firstBlock);
}

这真的是你的意思吗？ (我怀疑用“一些 block ”之类的东西做这个抽象会让它比实际情况复杂得多，而且你真的是想问一些相关的问题而不是这个问题。而且我认为你的意思是“执行”当你说“实现。”)