runtime的用法

• 1.使用runtime改变变量值

 //成员变量个数
    unsigned int count = 0;
    //获取所引用的实例变量
    Ivar *ivars = class_copyIvarList([Preson class], &count);
    
    //遍历
    for (int i = 0; i < count; i++) {
        //取出第i位置成员变量
        Ivar ivar = ivars[i];
        
        //查看成员变量
        const char *name = ivar_getName(ivar);
        
        NSString *key = [NSString stringWithUTF8String:name];
        
        if ([key isEqualToString:@"_name"]) {
            object_setIvar(self.person, ivar, @"name1");
            break;
        }

• 2.使用runtime交换方法

//获取方法
    Method m1 = class_getInstanceMethod([self.person class], @selector(firstMethod));
    Method m2 = class_getInstanceMethod([self.person class], @selector(secondMethod));
    
    method_exchangeImplementations(m1, m2);
}

• 3.使用runtime添加方法

//"v@:@" v表示void，@表示id，:表示SEL
    class_addMethod([self.person class], @selector(run:), (IMP)runMethod, "v@:@")

• 4.使用runtime给分类扩展属性

- (void)setNick:(NSString *)nick
{
    objc_setAssociatedObject(self, &name, nick, OBJC_ASSOCIATION_COPY_NONATOMIC);
}

- (NSString *)nick
{
    return objc_getAssociatedObject(self, &name);
}