objective-c - NSTimer代码永远执行

Question

这是我的代码。我希望计时器在启动后的5秒钟内停止，但事实并非如此。这是怎么了

-(void)loadView
{
NSTimeInterval startTime = [NSDate timeIntervalSinceReferenceDate];



NSTimer *timer = [NSTimer scheduledTimerWithTimeInterval:0.0
                                 target:self
                               selector:@selector(targetMethod:)
                               userInfo:nil
                                repeats:YES];
if([NSDate timeIntervalSinceReferenceDate] - startTime >= 5) {
    [timer invalidate];
}

}

-(void)targetMethod:(NSTimer *)timer {


    NSLog(@"bla");
}

Answer 1

默认情况下，NSDate的timeIntervalSinceReferenceDate返回2001年1月1日。相减相同的值将始终为0。

苹果的文档:
https://developer.apple.com/library/mac/ipad/#documentation/Cocoa/Reference/Foundation/Classes/NSDate_Class/Reference/Reference.html

这是一个主意:
在您的.h中

@interface MyClass : NSObject

@property (nonatomic, retain) NSTimer *timer;

- (void)targetMethod:(NSTimer *)timer;
- (void)cancelTimer;

@end

在您的.m中

@implementation MyClass

@synthesize timer;

-(void)loadView
{
    self.timer = [NSTimer scheduledTimerWithTimeInterval:0.0
                                             target:self
                                           selector:@selector(targetMethod:)
                                           userInfo:nil
                                            repeats:YES];
    [self performSelector:@selector(cancelTimer) withObject:nil afterDelay:5.0];
}

-(void)cancelTimer {
    [self.timer invalidate];
}

-(void)targetMethod:(NSTimer *)timer {
    NSLog(@"bla");
}