NSTimer不调用方法

Question

我现在真的很沮丧,谷歌搜索整个互联网,偶然发现,仍然没有找到解决方案.

我正在尝试实现NSTimer,但我定义的方法不会被调用.(正确设置秒数,使用断点检查).这是代码:

- (void) setTimerForAlarm:(Alarm *)alarm {
    NSTimeInterval seconds = [[alarm alarmDate] timeIntervalSinceNow];
    theTimer = [NSTimer timerWithTimeInterval:seconds 
                            target:self 
                          selector:@selector(showAlarm:)
                          userInfo:alarm repeats:NO];
}

- (void) showAlarm:(Alarm *)alarm {
    NSLog(@"Alarm: %@", [alarm alarmText]);
}

对象"theTimer"用@property定义:

@interface FooAppDelegate : NSObject <NSApplicationDelegate, NSWindowDelegate>  {
@private

    NSTimer *theTimer;

}

@property (nonatomic, retain) NSTimer *theTimer;

- (void) setTimerForAlarm:(Alarm *)alarm;
- (void) showAlarm:(Alarm *)alarm;

我究竟做错了什么？

Answer 1

timerWithTimeInterval只是创建一个计时器,但不会将它添加到任何运行循环中以便执行.尝试

self.theTimer = [NSTimer scheduledTimerWithTimeInterval:seconds 
                        target:self 
                      selector:@selector(showAlarm:)
                      userInfo:alarm repeats:NO];

代替.

Answer 2

另外不要忘记检查是否

+ (NSTimer *)scheduledTimerWithTimeInterval:(NSTimeInterval)seconds 
                                     target:(id)target 
                                   selector:(SEL)aSelector 
                                   userInfo:(id)userInfo 
                                    repeats:(BOOL)repeats 

在主线程中调用.

Answer 3

您已经创建了一个NSTimer对象,但尚未安排它运行.timerWithTimeInterval:target:selector:userInfo:repeats:创建一个计时器,您可以安排稍后运行,例如,在应用程序启动时创建计时器,并在用户按下按钮时开始计时.要么打电话

[[NSRunLoop currentRunLoop] addTimer:theTimer forMode:NSDefaultRunLoopMode]

在setTimerForAlarm结束或替换

theTimer = [NSTimer timerWithTimeInterval:seconds 
                            target:self 
                          selector:@selector(showAlarm:)
                          userInfo:alarm repeats:NO];

同

theTimer = [NSTimer scheduledTimerWithTimeInterval:seconds 
                            target:self 
                          selector:@selector(showAlarm:)
                          userInfo:alarm repeats:NO];

它创建一个计时器并立即安排它.