Question

I am trying to increase a variable’s value while uibutton is kept pressing. But when user leaves button, increasing of variable’s value will be stopped.

i have tried using threads with touch down and touchupinside but couldn’t make it work.

-(void) changeValueOfDepthFields:(UIButton *)sender {
    if (pressing) 
        pressing = NO;
    else 
        pressing = YES;

    pressingTag = 0;

    while (pressing) {

    [NSThread detachNewThreadSelector:@selector(increaseValue) toTarget:self withObject:nil];
    }
}

- (void) stopValueChange:(UIButton *)sender {

    pressing = NO;
}


[fStopUp addTarget:self action:@selector(changeValueOfDepthFields:) forControlEvents:UIControlEventTouchDown];
[fStopUp addTarget:self action:@selector(stopValueChange:) forControlEvents:UIControlEventTouchUpInside];


- (void) increaseValue {

    NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];

    fstopVal = fstopVal + 0.1;

    [self performSelectorOnMainThread:@selector(changeTextOfValues) withObject:nil waitUntilDone:YES];
    [pool release];
}


- (void) changeTextOfValues {
     fStopField.text = [NSString stringWithFormat:@"%.02f", fstopVal];
}

I wonder if there is an alternative way to do this or not. It seems very simple but couldn’t think of any other solution than this one.

Answer 1

It is much easier to use an NSTimer.

- (void)changeValueOfDepthFields:(UIButton *)sender
{
    if (!self.timer) {
        self.timer = [NSTimer scheduledTimerWithTimeInterval:1.0 target:self selector:@selector(increaseValue) userInfo:nil repeats:YES];
    }
}

- (void)stopValueChange:(UIButton *)sender
{
    if (self.timer) {
        [self.timer invalidate];
        self.timer = nil;
    }
}

- (void)increaseValue
{
    fstopVal = fstopVal + 0.1;
    fStopField.text = [NSString stringWithFormat:@"%.02f", fstopVal];
}

Note: The previous code is just for reference, I didn’t do any memory management for example.