How to set UIPageControl with image in iOS8 Objective c? - ios

Question

I want to set UIPageControl with images in the place of dots. I implemented the following code but it always crashing.Please help me.
-(void)updateDots
{
for (int i=0; i<[_pageControl.subviews count]; i++) {
UIImageView *dot = [_pageControl.subviews objectAtIndex:i];
if (i==_pageControl.currentPage)
dot.image = [UIImage imageNamed:#"on.png"];
else
dot.image = [UIImage imageNamed:#"off.png"];
}
}
In iOS8,i got the following error
*** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[UIView setImage:]:
unrecognized selector sent to instance 0x7f9dd9eaabb0'

Answer 1

You shouldn't assume that the UIPageControl will contain UIImageViews (it doesn't).
Here's how to do this with public APIs:
- (void)updateDots
{
// this only needs to be done one time
// 7x7 image (#1x)
_pageControl.currentPageIndicatorTintColor = [UIColor colorWithPatternImage:[UIImage imageNamed:#"on.png"]];
_pageControl.pageIndicatorTintColor = [UIColor colorWithPatternImage:[UIImage imageNamed:#"off.png"]];
}

Answer 2

you are getting UIView in for loop. check if dot is UIImageView Class then set image.
id object = [_pageControl.subviews objectAtIndex:i];
if([object isKindOfClass:[UIImageView Class]])
{
UIImageView *dot = (UIImageView *)object;
if (i==_pageControl.currentPage)
dot.image = [UIImage imageNamed:#"on.png"];
else
dot.image = [UIImage imageNamed:#"off.png"];
}
Hope it will help you.

Answer 3

Remember, subviews don't always have to be UIImageViews. For example, UITableViewCells often have enclosing views or so within them. You need to make the change below.
-(void)updateDots
{
for (int i=0; i<[_pageControl.subviews count]; i++) {
if ([[_pageControl.subviews objectAtIndex:i] isKindOfClass:[UIImageView Class]])
{
UIImageView *dot = (UIImageView *)[_pageControl.subviews objectAtIndex:i];
if (i==_pageControl.currentPage)
dot.image = [UIImage imageNamed:#"on.png"];
else
dot.image = [UIImage imageNamed:#"off.png"];
}
}
}
I've noticed that in a UITableViewCell, there is always an enclosing UIView for the cell content. You need to recursively go into this view to find the UIImageView you are looking for.