UILable自定义内边距属性（UIEdgeInsets contentInset）

UILabel没有类似于UITextView中的contentInset属性可以自定义设置显示内容的内边距

可以通过给UILabel添加类目扩展自定义一个contentInset属性实现设置UILabel的内边距

给UILable添加扩展类目（UILabel+Insets）

UILabel+Insets.h 文件

#import <UIKit/UIKit.h>
NS_ASSUME_NONNULL_BEGIN
@interface UILabel (Insets)
/**
和UITextView相似，内边距属性
控制字体与控件边界的间隙
*/
@property (nonatomic, assign) UIEdgeInsets contentInsets;
@end
NS_ASSUME_NONNULL_END

UILabel+Insets.m 文件

#import "UILabel+Insets.h"

@implementation UILabel (Insets)
static char kContentInsetsKey;

static char kShowContentInsetsKey;
- (void)setContentInsets:(UIEdgeInsets)contentInsets{
    objc_setAssociatedObject(self, &kContentInsetsKey, NSStringFromUIEdgeInsets(contentInsets), OBJC_ASSOCIATION_COPY_NONATOMIC);
    objc_setAssociatedObject(self, &kShowContentInsetsKey, @YES, OBJC_ASSOCIATION_COPY_NONATOMIC);
}
- (UIEdgeInsets)contentInsets{
    return UIEdgeInsetsFromString(objc_getAssociatedObject(self, &kContentInsetsKey));
}
+ (void)load{
    [super load];
// class_getInstanceMethod()
    Method fromMethod = class_getInstanceMethod([self class], @selector(drawTextInRect:));
    Method toMethod = class_getInstanceMethod([self class], @selector(tt_drawTextInRect:));
// class_addMethod()
    if (!class_addMethod([self class], @selector(drawTextInRect:), method_getImplementation(toMethod),
                         method_getTypeEncoding(toMethod))) {
        method_exchangeImplementations(fromMethod, toMethod);
    }
}

- (void)__drawTextInRect:(CGRect)rect{
    id show = objc_getAssociatedObject(self, &kShowContentInsetsKey);
    if (show) {
        rect = UIEdgeInsetsInsetRect(rect, self.contentInsets);
    }
    [self __drawTextInRect:rect];
}
@end

使用效果杠杠滴

label.contentInsets = UIEdgeInsetsMake(10.f, 10.f, 10.f, 10.f)

效果对比

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