increase a value while uibutton is kept pressing in iphone

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.

check below function. May it will help you rather code that much and let me know if you need any other optimization. — Kuldeep, Mar 23 '12 at 13:04
You should consider if a "touch and hold" is the correct gesture to be using. iOS users are used to swipe up/down or touch and hold then slide up/down for adjusting values like that rather than touch and hold which is more of a mouse gesture. — Nick Bull, Mar 23 '12 at 13:12
see UIStepper. Apple added a "touch and hold" UIControl. It can't be more correct. — Matthias Bauch, Mar 23 '12 at 13:17
@MatthiasBauch It's always nice to learn something new! Thanks for that. — Nick Bull, Mar 23 '12 at 20:15

sch · Accepted Answer · 2012-03-23T13:12:56.003

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.

increase a value while uibutton is kept pressing in iphone

1 Answers1