Slider Bar should appear as it moves towards its right - iphone

Question

Im my app, i need a slider with no bar initially. And as the user changes it, it should be visible.
As the user slides the thumb of the slider to the right the slider bar should start appearing on the left side.
Please share anything you have in your mind.
Thanks,

Answer 1

I've never tried this but I suppose it's possible. It sounds like a bad idea from a user-experience perspective, but that's outside the scope of this answer.
You can change the min and max images for a slider using the code below. You could add in some logic to hide these images initially (or set these images to transparent PNGs). Add a method called - (void)sliderAction:(id)sender which will be called when the slider is changed. Add logic there to change the images to something visible, or un-hide the images.
UIImage *minImage = [UIImage imageNamed:#"min.png"];
UIImage *maxImage = [UIImage imageNamed:#"max.png"];
UIImage *thumbImage= [UIImage imageNamed:#"thumb.png"];
minImage=[minImage stretchableImageWithLeftCapWidth:10.0 topCapHeight:0.0];
maxImage=[maxImage stretchableImageWithLeftCapWidth:10.0 topCapHeight:0.0];
UISlider* customSlider = [[UISlider alloc] initWithFrame:CGRectMake(30, 100, 200, 50)];
[customSlider setMinimumTrackImage:minImage forState:UIControlStateNormal];
[customSlider setMaximumTrackImage:maxImage forState:UIControlStateNormal];
[customSlider setThumbImage:thumbImage forState:UIControlStateNormal];
customSlider.minimumValue = 0.0;
customSlider.maximumValue = 100.0;
customSlider.continuous = YES;
customSlider.value = 50.0;
[customSlider addTarget:self action:#selector(sliderAction:) forControlEvents:UIControlEventValueChanged];
[self.view addSubview:customSlider];
[customSlider release];