实现效果

直接上代码

.h文件

#import <UIKit/UIKit.h>

@interface SXW_BUtton : UIButton



-(instancetype)initWithCoder:(NSCoder *)aDecoder;
-(instancetype)initWithFrame:(CGRect)frame;


-(CGRect)imageRectForContentRect:(CGRect)contentRect;
-(CGRect)titleRectForContentRect:(CGRect)contentRect;


@end

.m文件

#import "SXW_BUtton.h"

@interface SXW_BUtton ()

@property (nonatomic,strong) UIFont *myFont;

@end


@implementation SXW_BUtton





#pragma mark - 重写button创建方法

-(instancetype)initWithCoder:(NSCoder *)aDecoder{
    if (self = [super initWithCoder:aDecoder]) {
        [self setup];
    }
    return self;
}

-(instancetype)initWithFrame:(CGRect)frame{
    if (self = [super initWithFrame:frame]) {
        [self setup];
    }
    return self;
}

-(void)setup{
    //设置文字字体
    self.myFont = [UIFont systemFontOfSize:15.0];
    self.titleLabel.font = self.myFont;
}


#pragma mark - 重写button内容布局方法

-(CGRect)imageRectForContentRect:(CGRect)contentRect{
    
    CGFloat PADDING = 5;
    //获取文字
    NSString *title = self.currentTitle;
    
    //文字高度
    CGFloat titleH = [self getRectWithTitle:title].size.height;
    //    NSLog(@"titleH = %f", titleH);
    
    //image的x、y、w、h
    CGFloat imageH = (contentRect.size.height)/2;
    CGFloat imageW = imageH;
    CGFloat imageX = (contentRect.size.width - imageW) / 2;
    CGFloat imageY = (contentRect.size.height - imageH - titleH - PADDING) / 2;
    
    return CGRectMake(imageX, imageY, imageW, imageH);
}


-(CGRect)titleRectForContentRect:(CGRect)contentRect{
    
    
    CGFloat PADDING = 5;
    
    //获取文字
    NSString *title = self.currentTitle;
    
    //文字的Rect
    CGRect titleRect = [self getRectWithTitle:title];
    
    //btn的高
    CGFloat btnH = contentRect.size.height;
    
    //title的x、y、h
    CGFloat titleW = titleRect.size.width;
    CGFloat titleH = titleRect.size.height;
    CGFloat titleX = (contentRect.size.width - titleW)/2;
    CGFloat titleY = (btnH*1.5 - titleH + PADDING) / 2;   //此行代码是相加减后的数学公式，不用纠结！
    
    return CGRectMake(titleX, titleY, titleW, titleH);
}


#pragma mark - 获取文字Rect

-(CGRect)getRectWithTitle:(NSString *)title{
    //NSLog(@"title = %@", title);
    
    CGSize maxSize = CGSizeMake(MAXFLOAT, MAXFLOAT);
    NSMutableDictionary *md = [NSMutableDictionary dictionary];
    md[NSFontAttributeName] = self.myFont;
    
    return [title boundingRectWithSize:maxSize options:NSStringDrawingUsesLineFragmentOrigin attributes:md context:nil];
}