如何在后台线程上执行?即使用户按下主页按钮,也应该在后台继续执行。
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1 回答
8
将这些属性添加到您的 .h 文件中
@property (nonatomic, strong) NSTimer *updateTimer;
@property (nonatomic) UIBackgroundTaskIdentifier backgroundTask;
现在假设您对按钮有一个操作 --> btnStartClicked 那么您的方法将是:
-(IBAction)btnStartClicked:(UIButton *)sender {
self.updateTimer = [NSTimer scheduledTimerWithTimeInterval:0.5
target:self
selector:@selector(calculateNextNumber)
userInfo:nil
repeats:YES];
self.backgroundTask = [[UIApplication sharedApplication] beginBackgroundTaskWithExpirationHandler:^{
NSLog(@"Background handler called. Not running background tasks anymore.");
[[UIApplication sharedApplication] endBackgroundTask:self.backgroundTask];
self.backgroundTask = UIBackgroundTaskInvalid;
}];
}
-(void)calculateNextNumber{
@autoreleasepool {
// this will be executed no matter app is in foreground or background
}
}
如果您需要停止它,请使用此方法,
- (IBAction)btnStopClicked:(UIButton *)sender {
[self.updateTimer invalidate];
self.updateTimer = nil;
if (self.backgroundTask != UIBackgroundTaskInvalid)
{
[[UIApplication sharedApplication] endBackgroundTask:self.backgroundTask];
self.backgroundTask = UIBackgroundTaskInvalid;
}
i = 0;
}
于 2013-08-31T09:37:12.833 回答