NSTimer回调在后台线程上 [英] NSTimer callback on background thread

问题描述

我的 NSTimer 定义如下：

timer = [NSTimer scheduledTimerWithTimeInterval:30
                                         target:self
                                       selector:@selector(fooBar)
                                       userInfo:nil
                                        repeats:YES];
[[NSRunLoop mainRunLoop] addTimer:timer forMode:NSRunLoopCommonModes];

我想让它调用回调函数 fooBar 在这种情况下使用后台线程。但当我用检查if（[NSThread mainThread]）我总是在主线程上获取它。除了从回调函数调度线程之外还有其他方法吗？

I want it to call the call back function fooBar in this case using a background thread. But when I check with if ([NSThread mainThread]) i'm always getting it on the main thread. Is there any other way aside from dispatching a thread from the callback function?

推荐答案

您正在将计时器添加到主线程。您的回电也将在主线程中。要在后台线程中安排计时器，我认为您需要使用NSOperation子类并从操作的 main 方法中将计时器安排到[NSRunLoop currentRunLoop]。

You are adding the timer to main thread. Your call back will also be in main thread. To schedule the timer in a background thread, I think you need to use NSOperation subclass and schedule the timer to [NSRunLoop currentRunLoop] from inside the operation's main method.

#import <Foundation/Foundation.h>

@interface BackgroundTimer : NSOperation
{
    BOOL _done;
}
@end



#import "BackgroundTimer.h"

@implementation BackgroundTimer

-(void) main
{
    if ([self isCancelled])
    {
        return;
    }

    NSTimer *timer = [NSTimer scheduledTimerWithTimeInterval:30
                                             target:self
                                           selector:@selector(fooBar)
                                           userInfo:nil
                                            repeats:YES];

    [[NSRunLoop currentRunLoop] addTimer:timer forMode:NSRunLoopCommonModes];

    //keep the runloop going as long as needed
    while (!_done && [[NSRunLoop currentRunLoop] runMode:NSDefaultRunLoopMode
                                              beforeDate:[NSDate distantFuture]]);

}

@end

这篇关于NSTimer回调在后台线程上的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！