如何将一个块作为参数传递给Objective C中的另一个块 [英] How to pass a block as an argument into another block in Objective C

问题描述

我正在尝试定义一个以块为参数的块.

I'm trying to define a block that takes a block as an argument.

下面的代码行有什么问题?

What's wrong with the following line of code?

id (^cacheResult)(NSString *, id(^)(void)) = ^(NSString *name, id(^)(void)block) {
    NSObject *item = nil;
    block();
    return item;
};

为什么编译器会不断给出Parameter name omitted和Expected ")"之类的错误?

Why does the compiler keep giving errors like Parameter name omitted and Expected ")"?

推荐答案

id (^cacheResult)(NSString *, id(^)(void)) = ^(NSString *name, id(^block)(void)) {
    NSObject *item = nil;
    block();
    return item;
};

块与函数指针的语法相似.您必须在^

Blocks have similar syntax to function pointers. You have to declare block name after the ^

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