Triple Two, LLC.

I had a UIImageView control set up in one of my Views using Interface Builder, but I wanted to resize the UIImageView control programmatically depending on the device’s screen size.  I spent several hours trying all sorts of techniques, but I always had problems.  If I resized the UIImageView’s frame in viewDidLoad, it simply wouldn’t work.  If I resized its frame in viewDidAppear, it would work but the user would see the original-sized image before switching to the updated size which I felt was ugly and unnecessary.

I finally found a solution that would show the correctly resized UIImageView right away, but it required me to remove the UIImageView from my .XIB file, remove the outlet from Interface Builder, and remove the IBOutlet from my header file.  Then I simply programmatically added the UIImageView to the view in my viewDidLoad like so:

UIImageView *imageView = [[UIImageView alloc] initWithFrame:CGRectMake(20, 173, 728, 771)];
imageView.contentMode = UIViewContentModeScaleAspectFit;
imageView.image = [UIImage imageNamed:@"tutorial1.png"];
[self.view addSubview:imageView];

I was recently at wit’s end with what seemed like it should be a non-issue: I had taken a screenshot of my iPhone, cropped the image down to a single button, and was then trying to display it as the background image on a UIButton. The problem was that the image would appear twice as large. After stepping through the code, I realized that the UIImage object had a scale value of 1.0f instead of 2.0f like it should (I have an iPhone 5 with Retina Display). After some snooping around in Apple’s UIImage reference, I realized the fix was simple: I just had to add “@2x” to my image’s filename.  BUT there is one caveat:  when referencing the image’s filename in your code, do NOT add the “@2x”.

For example, if your image filename is “HelpIcon@2x.png”:

INCORRECT (image has scale factor of 1.0f and is too large)

[button setBackgroundImage: [UIImage imageNamed:@"HelpIcon@2x.png"] forState:UIControlStateNormal];

CORRECT (image has scale factor of 2.0f)

[button setBackgroundImage: [UIImage imageNamed:@"HelpIcon.png"] forState:UIControlStateNormal];