Iphone 使用nsrunlop

我正在viewDidLoad中运行2个方法，在它们之间运行nsrunlop 10秒

-(void)nextImage{ //charging a random image in the image view

    index = [[NSArray alloc]initWithObjects:@"1.jpg",@"2.jpg",@"3.jpg",@"4.jpg",@"5.jpg",nil];
    NSUInteger randomIndex = arc4random() % [index count];
    NSString *imageName = [index objectAtIndex:randomIndex];
    NSLog(@"%@",imageName);
    self.banner=[UIImage imageNamed:imageName];
    self.imageView.image=banner;
    [imageName release];
}

-(void)horror{

    self.banner=[UIImage imageNamed:@"Flo.jpg"];
    self.imageView.image=banner;
    NSString *path = [NSString stringWithFormat:@"%@%@",[[NSBundle mainBundle] resourcePath],@"/scream.wav"];
    SystemSoundID soundID;
    NSURL *filePath = [NSURL fileURLWithPath:path isDirectory:NO];
    AudioServicesCreateSystemSoundID((CFURLRef)filePath, &soundID);
    AudioServicesPlaySystemSound(soundID);

}

- (void)viewDidLoad
{

    [self nextImage];

    [[NSRunLoop currentRunLoop] runUntilDate:[NSDate dateWithTimeIntervalSinceNow:10.0]];

    [self horror];

    [super viewDidLoad];
}

---

这里的图像不变，黑屏，10秒后我只看到[恐怖]的结果。另一方面，当我仅在视图中保留[nextImage]并加载图像更改时，我认为nsrunlop出现问题，您不应该在大多数时间直接使用运行循环。方法

runUntilDate:

没有您认为的功能。对于您的用例，您应该设置一个计时器：

- (void)viewDidLoad
{
    [self nextImage];
    [NSTimer scheduledTimerWithTimeInterval: 10.0 target: self selector: @selector(horror) userInfo: nil repeats: NO];
    [super viewDidLoad];
}

计时器将在10秒后触发（

timeInterval:10.0

），然后使目标对象（本例中的视图控制器是由于

target:self

）执行方法

horror

（由于

选择器：@selector（horror）

）

如果您的视图控制器有可能在时间过去之前变为非活动状态，请在ivar中保护计时器实例，然后取消它：

...
NSTimer* timer = [NSTimer scheduledTimerWithTimeInterval: 10.0 target: self selector: @selector(horror) userInfo: nil repeats: NO];
self.myTimerProperty = timer;
...

...
if (self.myTimerProperty)
{
    // Ok. Since we have a timer here, we must assume, that we have set it
    // up but it did not fire until now. So, cancel it 
    [self.myTimerProperty invalidate];
    self.myTimerProperty = nil;
}
...

当您需要取消时：

...
NSTimer* timer = [NSTimer scheduledTimerWithTimeInterval: 10.0 target: self selector: @selector(horror) userInfo: nil repeats: NO];
self.myTimerProperty = timer;
...

...
if (self.myTimerProperty)
{
    // Ok. Since we have a timer here, we must assume, that we have set it
    // up but it did not fire until now. So, cancel it 
    [self.myTimerProperty invalidate];
    self.myTimerProperty = nil;
}
...

顺便说一句，如果您正在执行此操作，那么从中清除计时器属性可能是一个好主意 在回调方法中：

- (void) horror
{
    self.myTimerProperty = nil;
    ... other horrible stuff ...
}