Foundation-NSMutableDictionary

最新推荐文章于 2022-06-06 14:58:36 发布

xiaochou_yuer

最新推荐文章于 2022-06-06 14:58:36 发布

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文章标签： Foundation NSMutableDictionary 可变字典

本文链接：https://blog.youkuaiyun.com/xiaochou_yuer/article/details/50328683

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本文探讨了Objective-C与Swift两种编程语言在iOS开发领域的应用与区别，包括其优势、使用场景及实际案例分析。

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<span style="font-size:14px;">#import <Foundation/Foundation.h>

int main(int argc, const char * argv[]) {
    @autoreleasepool {
        
        //可变字典  NSMutableDictionary
        //1.初始化
        //创建一个空字典
        NSMutableDictionary *mDictionary1 = [NSMutableDictionary dictionary];
        
        
        //创建有一个键值对的可变字典
        NSMutableDictionary *mDictionary2 = [NSMutableDictionary dictionaryWithObject:@"Clown" forKey:@"name"];
        
        //创建多个键值对的可变字典
        NSMutableDictionary *mDictionary3 = [NSMutableDictionary dictionaryWithObjectsAndKeys:@"Clown", @"name", @21, @"age", @"GZ", @"address", nil];
        
        //通过另一个字典创建一个字典
        NSMutableDictionary *mDictionary4 = [NSMutableDictionary dictionaryWithDictionary:mDictionary3];
        
        NSEnumerator *enumerator = [[mDictionary3 allKeys]objectEnumerator];
        NSString *key;
        while (key = [enumerator nextObject]) {
//            NSLog(@"%@ = %@", key, mDictionary3[key]);
        }
        
        
        for (NSString *key in mDictionary3.allKeys) {
//            NSLog(@"%@ = %@", key, mDictionary3[key]);
        }
        
        //可变字典独有的初始化方法
        //创建了初始大小为10个键值对的可变字典，同样的这一个参数只是初始的大小，它是用来提高程序的效率的，并没有限制字典的大小，如果继续往里面添加数据，字典的元素个数会继续增加
        NSMutableDictionary *mDictionary5 = [NSMutableDictionary dictionaryWithCapacity:10];
        
        //从本地读取字典
        NSMutableDictionary *mDictionary6 = [NSMutableDictionary dictionaryWithContentsOfFile:@""];
        
        //从网络读取字典
        NSMutableDictionary *mDictionary7 = [NSMutableDictionary dictionaryWithContentsOfURL:[NSURL URLWithString:@""]];
        
        
        //操作字典
        //增
        [mDictionary5 setValue:@"Clown" forKey:@"name"];
        [mDictionary5 setValue:@21 forKey:@"age"];
        
        //改(如果原来字典中已有了key这个关键字，那么这次新加的值就会覆盖掉原来关键字(键)key对应的值)
        [mDictionary5 setValue:@"Black" forKey:@"name"];
        
        //新语法改
        mDictionary5[@"name"] = @"White";
        
        //删除指定key的对象
        [mDictionary5 removeObjectForKey:@"name"];
        
        //删除所有key的对象
        [mDictionary5 removeAllObjects];
        
        NSLog(@"%@",mDictionary5);
        
        //例子
        NSMutableDictionary *mDictionary8 = [NSMutableDictionary dictionaryWithObjectsAndKeys:@"Clown", @"name", @21, @"age", @"GZ", @"address", @"Clown", @"name2", @"Clown", @"name3", nil];
        
//        NSEnumerator *enumerator1 = [mDictionary8.allValues objectEnumerator];
//        NSEnumerator *enumerator2 = [mDictionary8.allKeys objectEnumerator];
//        NSString *value1 = [enumerator1 nextObject];
//        NSString *key1 = [enumerator2 nextObject];
        NSArray *keyD8 = mDictionary8.allKeys;
        for (NSString *key in keyD8) {
//            NSString *string;
            
            //因为字典中存在 NSUInteger 的类型，所以对其进行拆包
//            if ([mDictionary8[key] isKindOfClass:[NSNumber class]]) {
//                int a = [mDictionary8[key] intValue];
//                string = [NSString stringWithFormat:@"%d",a];
//            }
//            else {
//                string = mDictionary8[key];
//            }
            
            //等价于以下方法
            //通过 value 来把相应的 key 找出来
            NSString *string = mDictionary8[key];
            if ([string isEqual:@"Clown"]) {
                NSLog(@"%@",key);
            }
        }
    }
    return 0;
}
</span>