Objective-C category for styling

Question

What is the best way to create re-usable styling for UI objects for iOS app?

Eg I want to use the same style for each UITextField - top/bottom line and thinking about creating a category to provide the styling and simply apply it in View Controller.

Is there any better solution to do this?

UITextField+TextFieldStyler.m

- (void)addTopBorderWithColor:(UIColor *)color
{
    CGRect topBorderFrame = CGRectMake(0, 0, self.bounds.size.width, 1.0);
    UIView *topBorder = [[UIView alloc] initWithFrame:topBorderFrame];
    topBorder.backgroundColor = color;

    [self addSubview:topBorder];
}

PXRLoginViewController.m

[self.nameFIeld addTopBorderWithColor:[UIColor whiteColor]];
[self.passwordField addTopBorderWithColor:[UIColor whiteColor]];

Answer 1

I believe that the approach you are using is completely fine. It's also used by Apple itself for the same use cases, looking at the doc

Note: Cocoa and Cocoa Touch include a variety of categories for some of the primary framework classes.

The string-drawing functionality mentioned in the introduction to this chapter is in fact already provided for NSString by the NSStringDrawing category for OS X, which includes the drawAtPoint:withAttributes: and drawInRect:withAttributes: methods. For iOS, the UIStringDrawing category includes methods such as drawAtPoint:withFont: and drawInRect:withFont:.

As you can see, they use the same pattern for extending the drawing behaviour of the NSString.