Question

This is from a category that I’m using to modify UIView. The code works, but in the first method (setFrameHeight) I’m using a block and in the second method (setFrameWidth) I’m not. Is there any way to use blocks more efficiently in this example?

typedef CGRect (^modifyFrameBlock)(CGRect);

- (void) modifyFrame:(modifyFrameBlock) block {
    self.frame = block(self.frame);
}

- (void) setFrameWidth:(CGFloat)newWidth {
    modifyFrameBlock b = ^CGRect (CGRect frame) { 
        frame.size.width = newWidth;
        return frame; 
    };      
    [self modifyFrame:b];
}

- (void) setFrameHeight:(CGFloat)newHeight {
    CGRect f = self.frame;
    f.size.height = newHeight;
    self.frame = f;
}

The answer may be that blocks are not appropriate for such short methods, or something. The syntax sure seems funky.

Answer 1

The only thing you gain is not declaring the local variable for the new rect, in exchange you need to define a block. That is not a good deal, especially as it distracts from what you are doing.

Note that your block-usage could be shortened a bit:

[self modifyFrame:^(CGRect frame) {
    frame.size.width = newWidth;
    return frame; 
}];

Or even:

[self modifyFrame:^(CGRect* frame) {
    frame->size.width = newWidth;
}];

With modifyFrame: being:

CGRect frame;
block(&frame);
self.frame = frame;

But i’d still limit such approaches to more complex methods that only require minor parts of the code to be different.