iOS 对UIButton的imageView和titleLabel进行重新布局

#import <UIKit/UIKit.h>

@interface AppDelegate : UIResponder <UIApplicationDelegate>

@property (strong, nonatomic) UIWindow *window;

@end

#import "AppDelegate.h"
#import "RootViewController.h"
@interface AppDelegate ()

@end

@implementation AppDelegate

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
    self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];
    // Override point for customization after application launch.
    self.window.backgroundColor = [UIColor whiteColor];

    self.window.rootViewController = [[RootViewController alloc] init];

    [self.window makeKeyAndVisible];
    return YES;
}

@end

#import <UIKit/UIKit.h>

@interface RootViewController : UIViewController

@end

#import "RootViewController.h"
#import "LFCustomButton.h"
@interface RootViewController ()

@end

@implementation RootViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    self.view.backgroundColor = [UIColor greenColor];

    LFCustomButton *btn = [LFCustomButton buttonWithType:UIButtonTypeCustom];
    btn.frame = CGRectMake(, , , );
    //注意:在此不能使用[btn setBackgroundImage:[UIImage imageNamed:@"label_comment@3x"] forState:0],否则达不到想要的效果
    [btn setImage:[UIImage imageNamed:@"label_comment@3x"] forState:];
    [btn setTitle:@"哈哈" forState:];
    [btn setTitleColor:[UIColor blackColor] forState:];
    [self.view addSubview:btn];

}

@end

#import <UIKit/UIKit.h>

@interface LFCustomButton : UIButton

@end

#import "LFCustomButton.h"
const double LFButtonScale = 0.7;
@implementation LFCustomButton
/**
 *  在layoutSubviews中修改布局
 */
- (void)layoutSubviews{
    [super layoutSubviews];

    //计算宽高
    float imgHeight = MIN(self.bounds.size.width, self.bounds.size.height*LFButtonScale);
    float imgWidth = imgHeight;
    //imageView的尺寸
    self.imageView.frame = CGRectMake((self.bounds.size.width - imgWidth)/2.0, ,imgWidth, imgHeight);
    //titleLabel的尺寸
    self.titleLabel.frame = CGRectMake(, self.bounds.size.height*LFButtonScale, self.bounds.size.width, self.bounds.size.height*(-LFButtonScale));
    self.titleLabel.textAlignment = NSTextAlignmentCenter;
}

@end