#import <UIKit/UIKit.h>

@interface UILabel (Attribute)

@property (nonatomic, copy) NSString *newText;

@property (nonatomic, strong) UIFont *newFont;

@end



#import "UILabel+Attribute.h"
#import "objc/Runtime.h"

@implementation UILabel (Attribute)

static  NSString * newFontKey = @"newFontKey";
static  NSString * newTextKey = @"newTextKey";

#pragma mark - 使用runtime增加newFont属性
-(UIFont *)newFont{
    
    return objc_getAssociatedObject(self, &newFontKey);
}

- (void)setNewFont:(UIFont *)newFont{
    
    objc_setAssociatedObject(self, &newFontKey, newFont, OBJC_ASSOCIATION_RETAIN_NONATOMIC);
    self.font = [newFont fontWithSize:newFont.pointSize/2];
}

#pragma mark - 使用runtime增加newFont属性
- (NSString *)newText{
    // 利用runtime添加属性
    return objc_getAssociatedObject(self, &newTextKey);
}

-(void)setNewText:(NSString *)newText{
    // 利用runtime添加属性
    objc_setAssociatedObject(self, &newTextKey, newText, OBJC_ASSOCIATION_RETAIN_NONATOMIC);
    NSMutableString *str = [[NSMutableString alloc] initWithString:newText];
    NSInteger count = str.length;
    for (int i = 1; i < count; i ++) {
        [str insertString:@"\n" atIndex:i*2-1];
    }
    self.text = str;
    self.numberOfLines = 0;
}

@end

调用

UILabel *showTitleLabel=[[UILabel alloc]initWithFrame:CGRectMake(20, 200, 50, 100)];  //在图片上面添加UILabel
    
 showTitleLabel.textColor=[UIColor whiteColor];
 showTitleLabel.textAlignment=NSTextAlignmentCenter;
 showTitleLabel.backgroundColor = [UIColor orangeColor];
 showTitleLabel.newFont=[UIFont systemFontOfSize:28];
 showTitleLabel.newText = @"给Label增加属性";
  [self.view addSubview:showTitleLabel];