Alter CGRect (or any struct)? - objective-c

Question

I do this quite a bit in my code:
self.sliderOne.frame = CGRectMake(newX, 0, self.sliderOne.frame.size.width, self.sliderOne.frame.size.height);
Is there any way to avoid this tedious code? I have tried this type of thing:
self.sliderOne.frame.origin.x = newX;
but I get a Lvalue required as left operand of assignment error.

Answer 1

I finally followed #Dave DeLong's suggestion and made a category. All you have to do is import it in any class that wants to take advantage of it.
UIView+AlterFrame.h
#import <UIKit/UIKit.h>
#interface UIView (AlterFrame)
- (void) setFrameWidth:(CGFloat)newWidth;
- (void) setFrameHeight:(CGFloat)newHeight;
- (void) setFrameOriginX:(CGFloat)newX;
- (void) setFrameOriginY:(CGFloat)newY;
#end
UIView+AlterFrame.m
#import "UIView+AlterFrame.h"
#implementation UIView (AlterFrame)
- (void) setFrameWidth:(CGFloat)newWidth {
CGRect f = self.frame;
f.size.width = newWidth;
self.frame = f;
}
- (void) setFrameHeight:(CGFloat)newHeight {
CGRect f = self.frame;
f.size.height = newHeight;
self.frame = f;
}
- (void) setFrameOriginX:(CGFloat)newX {
CGRect f = self.frame;
f.origin.x = newX;
self.frame = f;
}
- (void) setFrameOriginY:(CGFloat)newY {
CGRect f = self.frame;
f.origin.y = newY;
self.frame = f;
}
#end
I could DRY up the methods using blocks... I'll do that at some point soon, I hope.
Later: I just noticed CGRectOffset and CGRectInset, so this category could be cleaned up a bit (if not eliminated altogether).

Answer 2

Yeah, you have to do:
CGRect newFrame = self.sliderOne.frame;
newFrame.origin.x = frame.size.width - MARGIN * 2 - totalWidth;
self.sliderOne.frame = newFrame;
It sucks, I know. If you find yourself doing this a lot, you may want to add categories to UIView/NSView to alter this stuff for you:
#interface UIView (FrameMucking)
- (void) setWidth:(CGFloat)newWidth;
#end
#implementation UIView (FrameMucking)
- (void) setWidth:(CGFloat)newWidth {
CGRect f = [self frame];
f.size.width = newWidth;
[self setFrame:f];
}
#end
Etc.

Answer 3

The issue here is that self.sliderOne.frame.origin.x is the same thing as [[self sliderOne] frame].origin.x. As you can see, assigning back to the lValue here is not what you want to do.
So no, that "tedious" code is necessary, although can be shortened up a bit.
CGRect rect = thing.frame;
thing.frame = CGRectMake(CGRectGetMinX(rect), CGRectGetMinY(rect) + 10, etc...);