objective_c 第九章课后练习题答案

最新推荐文章于 2020-12-15 09:30:12 发布

原创最新推荐文章于 2020-12-15 09:30:12 发布 · 610 阅读

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本文通过几个具体的Objective-C编程示例介绍了动态类型检查的方法，包括如何判断对象是否属于特定类或类的实例，以及对象是否响应特定选择器。

本章例题比较简单不再一一列出

int main(int argc, const char * argv[]) {
    @autoreleasepool {
//第3题
        id dataValue;
        XYpoint *myXYpoint=[[XYpoint alloc]init];
        [myXYpoint setX:22 andY:33];
        dataValue=myXYpoint;
        [myXYpoint printf];

       
        //第5题
        Fraction *fraction=[[Fraction alloc]init];
        Complex *complex=[[Complex alloc]init];
        id number=[[Complex alloc]init];
        
        if([fraction isMemberOfClass:[Complex class]]==YES)
           NSLog(@"fraction is member of complex class");
        if([complex isMemberOfClass:[NSObject class]]==YES)
           NSLog(@"complex is member of NSObject class");
        if([complex isKindOfClass:[NSObject class]]==YES)
           NSLog(@"complex is kind of NSObject ");
        if([fraction isKindOfClass:[Fraction class]]==YES)
            NSLog(@"fraction is kind of Fraction ");
        if([fraction respondsToSelector:@selector(print)]==YES)
            NSLog(@"fraction responds to print:method");
        if([complex respondsToSelector:@selector(print)]==YES)
            NSLog(@"complex responds to print:method");
        if([Fraction instancesRespondToSelector:@selector(print)]==YES)
            NSLog(@"instances of Fraction respond to print:method ");
        if([number respondsToSelector:@selector(print)]==YES)
            NSLog(@"instances of number respond to print:method");
        if([number isKindOfClass:[complex class]]==YES)
            NSLog(@"number is kind of complex");
        if([[number class] respondsToSelector:@selector(alloc)]==YES)
            NSLog(@"number class respond to alloc method");
    }
    return 0;
}