Objective C - 块问题？

发布于 2024-11-01 06:48:51 字数 251 浏览 0 评论 0原文

我有以下方法

+ (NSString*)getMeMyString
{
   NSString *result;
   dispatch_async(dispatch_get_main_queue(), ^{
        result = [ClassNotThreadSafe getString];
    });
   return result;
}

如何使块同步完成其工作，以便在检索结果之前不会返回结果？

原文

I have the following method

+ (NSString*)getMeMyString
{
   NSString *result;
   dispatch_async(dispatch_get_main_queue(), ^{
        result = [ClassNotThreadSafe getString];
    });
   return result;
}

How can i make the block to do it's job synchronously, so that it doesn't return the result before it was retreived?

分享到QQ

分享到微博

如果你对这篇内容有疑问，欢迎到本站社区发帖提问参与讨论，获取更多帮助，或者扫码二维码加入 Web 技术交流群。

发布评论

需要登录才能够评论，你可以免费注册一个本站的账号。

不必了 2024-11-08 06:48:51

您正在调用 dispatch_async 来异步调度您的块。如果您的目标是阻止主线程，请尝试使用 dispatch_sync 或 dispatch_main。

+ (NSString*)getMeMyString
{
   __block NSString *result;
   dispatch_sync(dispatch_get_main_queue(), ^{
        result = [ClassNotThreadSafe getString];
    });
   return result;
}

Grand Central Dispatch 参考

You are calling dispatch_async which dispatches your block asynchronously. Try using dispatch_sync or dispatch_main if your goal is to block the main thread.

+ (NSString*)getMeMyString
{
   __block NSString *result;
   dispatch_sync(dispatch_get_main_queue(), ^{
        result = [ClassNotThreadSafe getString];
    });
   return result;
}

Grand Central Dispatch Reference

回复收藏 0 原文

漫漫岁月 2024-11-08 06:48:51

使用dispatch_sync而不是dispatch_async - 那么当前线程将被阻塞，直到该块在主线程上完成执行。

回复收藏 0 原文

你如我软肋 2024-11-08 06:48:51

既然您似乎想在不同的线程上执行一个方法并获取返回值，为什么不使用 NSInitation 呢？

SEL theSelector;
NSMethodSignature *aSignature;
NSInvocation *anInvocation;

theSelector = @selector(getString);
aSignature = [ClassNotThreadSafe instanceMethodSignatureForSelector:theSelector];
anInvocation = [NSInvocation invocationWithMethodSignature:aSignature];
[anInvocation setSelector:theSelector];

NSString *result;

[anInvocation performSelectorOnMainThread:@selector(invoke) withObject:nil waitUntilDone:YES];
[anInvocation getReturnValue:result];

Since it seems like you want to perform a method on a different thread and get a return value, why don't you use an NSInvocation?

SEL theSelector;
NSMethodSignature *aSignature;
NSInvocation *anInvocation;

theSelector = @selector(getString);
aSignature = [ClassNotThreadSafe instanceMethodSignatureForSelector:theSelector];
anInvocation = [NSInvocation invocationWithMethodSignature:aSignature];
[anInvocation setSelector:theSelector];

NSString *result;

[anInvocation performSelectorOnMainThread:@selector(invoke) withObject:nil waitUntilDone:YES];
[anInvocation getReturnValue:result];

回复收藏 0 原文

~没有更多了~