#define MyUIScreen  375  //UI设计原型图的手机尺寸宽度(6), 6p的--414

@implementation UIFont (Runtime)

+(void)load

{

    Method method = class_getClassMethod([self class], @selector(systemFontOfSize:));

    Method MyMethod = class_getClassMethod([self class], @selector(adapterFontOfSize:));

    method_exchangeImplementations(method, MyMethod);

}

+(UIFont *)adapterFontOfSize:(CGFloat)fontSize

{

    return [UIFont adapterFontOfSize:fontSize * [UIScreen mainScreen].bounds.size.width /MyUIScreen];

}

    UILabel * label = [[UILabel alloc]initWithFrame:CGRectMake(, , [UIScreen mainScreen].bounds.size.width, )];

    label.text = @"适配字体大小";

    label.backgroundColor = [UIColor yellowColor];

    label.font = [UIFont systemFontOfSize:];

    [self.view addSubview:label];