这是最简单方便的方法，我们可以使用runtime机制替换掉UILabel的初始化方法，在其中对label的字体进行默认设置。因为Label可以从initWithFrame、init和nib文件三个来源初始化，所以我们需要将这三个初始化的方法都替换掉。
#import@interface UILabel (QMChangeDefaultFont)
@end
#import "UILabel+QMChangeDefaultFont.h"
#import <objc/runtime.h>
#import@implementation UILabel (QMChangeDefaultFont)
/**
*每个NSObject的子类都会调用下面这个方法 在这里将init方法进行替换，使用我们的新字体
*如果在程序中又特殊设置了字体 则特殊设置的字体不会受影响 但是不要在Label的init方法中设置字体
*从init和initWithFrame和nib文件的加载方法 都支持更换默认字体
*/
+(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(QMBaseInit);
SEL swizzledSelector2 = @selector(QMBaseInitWithFrame:);
SEL swizzledSelector3 = @selector(QMBaseAwakeFromNib);
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)QMBaseInit
{
id __self = [self QMBaseInit];
UIFont * font = [UIFont fontWithName:@"这里输入你的字体名字" size:self.font.pointSize];
if (font) {
self.font=font;
}
return __self;
}
-(instancetype)QMBaseInitWithFrame:(CGRect)rect{
id __self = [self QMBaseInitWithFrame:rect];
UIFont * font = [UIFont fontWithName:@"这里输入你的字体名字" size:self.font.pointSize];
if (font) {
self.font=font;
}
return __self;
}
-(void)QMBaseAwakeFromNib{
[self QMBaseAwakeFromNib];
UIFont * font = [UIFont fontWithName:@"这里输入你的字体名字" size:self.font.pointSize];
if (font) {
self.font=font;
}
}
@end
/**
*每个NSObject的子类都会调用下面这个方法 在这里将init方法进行替换，使用我们的新字体
*如果在程序中又特殊设置了字体 则特殊设置的字体不会受影响 但是不要在Label的init方法中设置字体
*从init和initWithFrame和nib文件的加载方法 都支持更换默认字体
*/
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