ios - 自动减少自身的NSNumber-1

Question

好的，基本上，我正在尝试构建一些代码，以使NSNumber每分钟减少1，

到目前为止，这就是我所拥有的。

- (void)viewDidLoad {
[super viewDidLoad];
NSNumber *numVar = [NSNumber numberWithUnsignedChar:99];
[self num];
}
-(void)num{
usleep(60000000);
NSNumber *numVar = [NSNumber numberWithUnsignedChar:numVar-1];
[self num];
}

首先，它不会每分钟减少一次；其次，将初始numVar包含在viewDidLoad中是错误的吗？

Answer 1

我们尝试了这个，它可以很好地满足我们的需求:
您需要在代码中重新安排

- (void)viewDidLoad{
     NSTimer *timer;
     int minutes = 0;

     //Creating a label that shows the timer ; i assume you have one that is already linked
     _labelTimer.text = [NSString stringWithFormat:@"This is %i minute", minutes];

     //Creating the timer itself with the NSTimer object
     timer = [NSTimer scheduledTimerWithTimeInterval: 60.0 target: self selector:@selector(decreaseTimeCount) userInfo:nil repeats:YES];  

     //Note that 60 is the number of seconds before it calls the selector. You can use 1 if you want it to change your timer/clock every second
}
- (void)decreaseTimeCount{

    //The method changes the value of my variable and updates the label. If i'm at the 10th minute, i could do something, like perform a segue.

    minute+=1;
    _labTimer.text = [NSString stringWithFormat:@"This is %i minutes", minutes];

    if (minutes == 10){
        //do stuff 
    }

}