Question

In the following code I have a view object that is an instance of UIScrollView, if I run the code below I get warnings saying that "UIView might not respond to -setContentSize etc."

UIImage *image = [UIImage imageNamed:@"Snowy_UK.jpg"];
imageView = [[UIImageView alloc] initWithImage:image];
[[self view] addSubview:imageView];
[[self view] setContentSize:[image size]];
[[self view] setMaximumZoomScale:2.0];
[[self view] setMinimumZoomScale: [[self view] bounds].size.width / [image size].width];

I have checked the type of the object and [self view] is indeed a UIScrollView. I am guessing that this is just the compiler making a bad guess as to the type and the solution is simply to cast the object to the correct type manually, am I getting this right?

UIScrollView *scrollView = (UIScrollView *)[self view];

UIImage *image = [UIImage imageNamed:@"Snowy_UK.jpg"];
imageView = [[UIImageView alloc] initWithImage:image];
[[self view] addSubview:imageView];
[scrollView setContentSize:[image size]];
[scrollView setMaximumZoomScale:2.0];
[scrollView setMinimumZoomScale: [scrollView bounds].size.width / [image size].width];

cheers Gary.

Answer 1

If you defined the instance variable in a class of your own, you can of course declare it as:
UIScrollView *view; inside the class definition. If you’ve subclassed another class that has UIView *view; in the definition (I suspect that’s the case here), then the way you’re doing it above is probably the best way to satisfy the compiler.

You might also want to add an assert to check the class of the view at that point, so you get a reasonable error message if something goes wrong.