"__weak typeof(self) weakSelf = self;"预期的 ;在声明结束时 [英] "__weak typeof(self) weakSelf = self;" expected ; at end of declaration

问题描述

我在 Xcode 6.4 中打开了两个项目.两者都使用以下声明:

I have two projects open in Xcode 6.4. Both use the follow declaration:

- (void)startService
{
    __weak typeof(self) weakSelf = self;
    [self.messageOperationQueue addOperationWithBlock:^{
        NSDictionary *storedMessages = [mySettings get:kStorageName withDefault:@{} storageType:kMySettingsStorageTypeDiskMapped];
        [weakSelf.messages addEntriesFromDictionary:storedMessages];
    }];
}

然而，在一个项目中没有错误，而在另一个项目中我得到一个编译器错误:

However, in one project there are no errors, and in the other project I get a compiler error:

Expected ';' at end of declaration

它要我在 __weak typeof(self) 后面加一个分号.我怀疑我只是在做一些非常愚蠢的事情，但我无法弄清楚是什么.另外，我知道我可以用 myClass * 替换 typeof(self).

It wants me to put a semi-colon after __weak typeof(self). I have suspicion that I'm just doing something really dumb, but I'm having trouble figuring out what. Also, I know I could replace the typeof(self) with myClass *.

推荐答案

使用 __typeof 而不是 typeof.

这是因为 __typeof 和 typeof 都是 C 的扩展，但是 typeof 只有在语言是 GNUXX C 的变体，但不适用于 CXX.

This is because both __typeof and typeof are extensions to C, but typeof is only enabled in Clang when the language is a GNUXX variant of C, but not for CXX.

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