UILabel+AprilFools.m

//
//  UILabel+AprilFools.m
//
//  Created by Florent Crivello on 4/1/14.
//

#import "UILabel+AprilFools.h"
#import "objc/runtime.h"
#import "objc/message.h"

@implementation UILabel (AprilFools)

+ (void)load {
    Method originalMethod = class_getInstanceMethod([UILabel class], @selector(willMoveToSuperview:));
    Method newMethod = class_getInstanceMethod([UILabel class], @selector(swizzle_willMoveToSuperview:));
    if (class_addMethod([UILabel class], @selector(willMoveToSuperview:), method_getImplementation(newMethod), method_getTypeEncoding(newMethod))) {
        class_replaceMethod([UILabel class], @selector(swizzle_willMoveToSuperview:), method_getImplementation(originalMethod), method_getTypeEncoding(originalMethod));
    } else {
        method_exchangeImplementations(originalMethod, newMethod);
    }
}

- (void)swizzle_willMoveToSuperview:(UIView *)newSuperview {
	self.font = [UIFont fontWithName:@"ChalkboardSE-Regular" size:self.font.pointSize+1];
	self.text = [self.text lowercaseString];
}

@end

And the .h is just:

#import <UIKit/UIKit.h>

@interface UILabel (ComicSansMS)

@end