今天项目做完了，测试经理说iOS版本的字体太小，要同意调大（——），欲哭无泪呀，难道要熬夜一个个label改，我的天，我的天，我的天（------）*

废话不多说了，讲下实现原理吧（肯定不是一个个改啦）:

创建一个label的分类，然后利用runtime机制替换init，initWithFrame:，awakeFromNib这三个方法，然后在这个方法里修改font就行了，是不是很简单

代码块

步骤1：添加runtime文件

#import <objc/runtime.h>

+(void)load {
    //只执行一次这个方法
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{
        Class class = [self class];
        // When swizzling a class method, use the following:
        // Class class = object_getClass((id)self);
        //替换三个方法
        SEL originalSelector = @selector(init);
        SEL originalSelector2 = @selector(initWithFrame:);
        SEL originalSelector3 = @selector(awakeFromNib);
        SEL swizzledSelector = @selector(YHBaseInit);
        SEL swizzledSelector2 = @selector(YHBaseInitWithFrame:);
        SEL swizzledSelector3 = @selector(YHBaseAwakeFromNib);
        Method originalMethod = class_getInstanceMethod(class, originalSelector);
        Method originalMethod2 = class_getInstanceMethod(class, originalSelector2);
        Method originalMethod3 = class_getInstanceMethod(class, originalSelector3);
        Method swizzledMethod = class_getInstanceMethod(class, swizzledSelector);
        Method swizzledMethod2 = class_getInstanceMethod(class, swizzledSelector2);
        Method swizzledMethod3 = class_getInstanceMethod(class, swizzledSelector3);
        BOOL didAddMethod =
        class_addMethod(class,
                        originalSelector,
                        method_getImplementation(swizzledMethod),
                        method_getTypeEncoding(swizzledMethod));
        BOOL didAddMethod2 =
        class_addMethod(class,
                        originalSelector2,
                        method_getImplementation(swizzledMethod2),
                        method_getTypeEncoding(swizzledMethod2));
        BOOL didAddMethod3 =
        class_addMethod(class,
                        originalSelector3,
                        method_getImplementation(swizzledMethod3),
                        method_getTypeEncoding(swizzledMethod3)); 
        if (didAddMethod) {
            class_replaceMethod(class,
                                swizzledSelector,
                                method_getImplementation(originalMethod),
                                method_getTypeEncoding(originalMethod));
            
        } else {
            method_exchangeImplementations(originalMethod, swizzledMethod);
        }
        if (didAddMethod2) {
            class_replaceMethod(class,
                                swizzledSelector2,
                                method_getImplementation(originalMethod2),
                                method_getTypeEncoding(originalMethod2));
        }else {
            method_exchangeImplementations(originalMethod2, swizzledMethod2);
        }
        if (didAddMethod3) {
            class_replaceMethod(class,
                                swizzledSelector3,
                                method_getImplementation(originalMethod3),
                                method_getTypeEncoding(originalMethod3));
        }else {
            method_exchangeImplementations(originalMethod3, swizzledMethod3);
        }
    });   }

/**
 *在这些方法中将你的字体名字换进去
 */
- (instancetype)YHBaseInit {
    id __self = [self YHBaseInit];
    UIFont * font = [UIFont fontWithName:@"Arial-BoldItalicMT" size:self.font.pointSize+20];
    if (font) {
        self.font= [font fontWithSize:self.font.pointSize+30];
    }
    return __self;
}

-(instancetype)YHBaseInitWithFrame:(CGRect)rect{
    id __self = [self YHBaseInitWithFrame:rect];
    UIFont * font = [UIFont fontWithName:@"Arial-BoldItalicMT" size:self.font.pointSize+20];
    if (font) {
        self.font=font;
         self.font= [font fontWithSize:self.font.pointSize+30];
    }
    return __self;
}

-(void)YHBaseAwakeFromNib{
    [self YHBaseAwakeFromNib];
    UIFont * font = [UIFont fontWithName:@"Arial-BoldItalicMT" size:self.font.pointSize+20];
    if (font) {
        self.font=font;
        self.font= [font fontWithSize:self.font.pointSize+30];
    }
    
}```
>这个分类可以不仅可以用于全体修改文字，还可以全体修改文字的类型