Why is the UIImageView not hiding when using a UISegmentedControl? - ios

Question

I have a UISegmentedControl where the first control will display the text within a UITextView while the second control displays a scrollable UIImageView.
In the initial startup, if I switch to the second control, the image displays and switching back to the first control, the image disappears and the UITextView shows.
However, when I switch to the second control the 2nd time and switch back to the first control, the image is still there and I cannot get the UITextView to show anymore.
My code has it to where the image is hidden and the text is shown in the first control, and vice versa in the second control.
Why was it working the first time, but then not working the second time I switched between controls?
What am I doing wrong?
Thanks
-(void)viewDidLoad
{
self.scrollView.delegate = self;
self.textView.text = #"THIS IS A TEST. THIS IS A TEST. THIS IS A TEST. THIS IS A TEST. THIS IS A TEST. THIS IS A TEST.";
self.textView.hidden = NO;
}
-(void)setScroller
{
CGSize scrollableSize = CGSizeMake(self.view.frame.size.width, self.view.frame.size.height);
[self.scrollView setContentSize:scrollableSize];
self.imageView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:#"test.png"] ];
self.imageView.frame = CGRectMake(0, 0, self.scrollView.frame.size.width, self.view.frame.size.height);
self.scrollView.backgroundColor = [UIColor blackColor];
self.scrollView.minimumZoomScale = 1.0 ;
self.scrollView.maximumZoomScale = self.imageView.image.size.width / self.scrollView.frame.size.width;
//self.scrollView.zoomScale = 1.0;
[self.scrollView addSubview:self.imageView];
}
-(UIView *)viewForZoomingInScrollView:(UIScrollView *)scrollView
{
return self.imageView;
}
- (IBAction)segmentedControl:(UISegmentedControl *)sender
{
if (self.segmentedControl.selectedSegmentIndex == 0)
{
// Display apppropriate info for About
self.imageView.hidden = YES;
self.textView.hidden = NO;
}
else
{
self.imageView.hidden = NO;
self.textView.hidden = YES;
[self setScroller];
}
}

Answer 1

You should remove [self setScroller]; from the - (IBAction)segmentedControl:(UISegmentedControl *)sender method, and put it in -(void)viewDidLoad instead. You're calling [self setScroller]; every time you switch to the second segment.
Your code should look like:
-(void)viewDidLoad
{
[super viewDidLoad];
self.scrollView.delegate = self;
[self setupScroller];
}
-(void)setupScroller
{
// Set contentSize
CGSize scrollableSize = CGSizeMake(self.view.frame.size.width, self.view.frame.size.height);
self.scrollView.contentSize = scrollableSize;
// Add textView
self.textView.text = #"THIS IS A TEST. THIS IS A TEST. THIS IS A TEST. THIS IS A TEST. THIS IS A TEST. THIS IS A TEST.";
self.textView.hidden = NO;
// Add ImageView
self.imageView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:#"test.png"]];
self.imageView.frame = CGRectMake(0, 0, self.scrollView.frame.size.width, self.view.frame.size.height);
self.imageView.hidden = YES;
[self.scrollView addSubview:self.imageView];
// Configure Zoom Scales and backgroundColor
self.scrollView.backgroundColor = [UIColor blackColor];
self.scrollView.minimumZoomScale = 1.0 ;
self.scrollView.maximumZoomScale = self.imageView.image.size.width / self.scrollView.frame.size.width;
}
-(UIView *)viewForZoomingInScrollView:(UIScrollView *)scrollView
{
return self.imageView;
}
- (IBAction)segmentedControl:(UISegmentedControl *)sender
{
if (self.segmentedControl.selectedSegmentIndex == 0)
{
// Display appropriate info for About
self.imageView.hidden = YES;
self.textView.hidden = NO;
}
else
{
self.imageView.hidden = NO;
self.textView.hidden = YES;
}
}

Answer 2

Your problem probably is that you creating a lot of instances of "imageView"
To solve your problem I suggest:
-(void)setScroller
{
CGSize scrollableSize = CGSizeMake(self.view.frame.size.width, self.view.frame.size.height);
[self.scrollView setContentSize:scrollableSize];
if(self.imageView == nil) {
self.imageView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:#"test.png"]];
[self.scrollView addSubview:self.imageView];
}
self.imageView.frame = CGRectMake(0, 0, self.scrollView.frame.size.width, self.view.frame.size.height);
self.scrollView.backgroundColor = [UIColor blackColor];
self.scrollView.minimumZoomScale = 1.0 ;
self.scrollView.maximumZoomScale = self.imageView.image.size.width / self.scrollView.frame.size.width;
//self.scrollView.zoomScale = 1.0;
[self.imageView setNeedsDisplay];
[self.imageView setImage:[UIImage imageNamed: #"test.png"]];
}
I've put only the Alloc of the self.imageView + the addSubView to the if,
All the rest are out side,
Now it will work