OC基础之字典，集合，字符串

最新推荐文章于 2020-06-29 16:22:45 发布

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最新推荐文章于 2020-06-29 16:22:45 发布

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分类专栏： iOS iOS从入门到精通

本文链接：https://blog.youkuaiyun.com/u014702332/article/details/50573555

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本文介绍了Objective-C中字典和数组的基本操作，包括初始化、遍历、增删改查等功能实现方式，展示了如何灵活运用这些集合来提升开发效率。

说明：OC里的集合，数组，等都可以类比java中集合数组的处理。

字典

        NSDictionary *dict1=[NSDictionary dictionaryWithObject:@"one" forKey:@"key1"];
        
        NSLog(@"%@",dict1);        //以多个元素进行初始化
        
        NSDictionary *dict2=[NSDictionary dictionaryWithObjectsAndKeys:@"one", @"key1",@"two",@"key2",@"three",@"key3", nil];
        
        NSLog(@"%@",dict2);
        
         NSLog(@"----%@",[dict2 objectForKey:@"key2"]);
        
        
        //遍历NSDictionary
        NSArray *objs = [dict2 allKeys];
        
        for (NSString *str in objs) {
            NSLog(@"----%@",str);
        
        }

打印结果

2016-01-31 16:33:27.817 OC[1766:156610] {
    key1 = one;
}
2016-01-31 16:33:27.818 OC[1766:156610] {
    key1 = one;
    key2 = two;
    key3 = three;
}
2016-01-31 16:33:27.818 OC[1766:156610] ----two
2016-01-31 16:33:27.819 OC[1766:156610] ----key1
2016-01-31 16:33:27.819 OC[1766:156610] ----key3
2016-01-31 16:33:27.819 OC[1766:156610] ----key2
Program ended with exit code: 0

集合

        //使用集合
        //使用数组
        NSArray *array = [NSArray arrayWithObjects:@"one",@"two",@"three",nil];

        //快速遍历
        for (NSString *str in array) {
            NSLog(@"----%@",str);
        }
        
        //索引访问
        for (NSInteger n; n< array.count; n++) {
            NSLog(@"%@",[array objectAtIndex:n]);
        }
        
        //使用NSEnumerator对象
        NSEnumerator *enumeator = [array objectEnumerator];
        NSString *item = nil;
        while ((item =[enumeator nextObject])) {
            NSLog(@"%@",item);
        }
      
        NSLog(@"last object %@",[array lastObject]);
        
        NSLog(@"first object %@",[array objectAtIndex:0]);

打印的值：

2016-01-31 16:06:44.836 OC[1675:149420] ----one
2016-01-31 16:06:44.837 OC[1675:149420] ----two
2016-01-31 16:06:44.837 OC[1675:149420] ----three
2016-01-31 16:06:44.837 OC[1675:149420] one
2016-01-31 16:06:44.837 OC[1675:149420] two
2016-01-31 16:06:44.837 OC[1675:149420] three
2016-01-31 16:06:44.837 OC[1675:149420] one
2016-01-31 16:06:44.837 OC[1675:149420] two
2016-01-31 16:06:44.837 OC[1675:149420] three
2016-01-31 16:06:44.838 OC[1675:149420] last object three
2016-01-31 16:06:44.838 OC[1675:149420] first object one
Program ended with exit code: 0

可变数组：

        //认识可变性
        NSMutableArray *array = [NSMutableArray array];
        [array addObject:@"one"];
        [array addObject:@"two"];
        [array addObject:@"three"];
        
        NSLog(@"删除之前%@",array);
        [array removeObject:@"one"];
         NSLog(@"删除之后%@",array);
        
        [array removeObjectAtIndex:0];
        
        [array replaceObjectAtIndex:0 withObject:@"oneoneone"];
        
        NSLog(@"%@",array);

打印结果：

2016-01-31 16:40:34.118 OC[1785:159199] 删除之前(
    one,
    two,
    three
)
2016-01-31 16:40:34.119 OC[1785:159199] 删除之后(
    two,
    three
)
2016-01-31 16:40:34.119 OC[1785:159199] (
    oneoneone
)
Program ended with exit code: 0

字符串：NSString,NSMutableString

    NSString *str;

        
        NSString *cardName = @"Ace";
        
        NSString *cardSuit = @"Spades";

        str = [NSString stringWithFormat:@"The winning card is %@ of %@.",cardName,cardSuit];
        
        NSLog(@"-----%@",str);
        
        //-----The winning card is Ace of Spades.
        
        NSString *str2 = @"this is a string of words";
    
        NSArray *words = [str2 componentsSeparatedByString:@" "];   //分割字符串 类似于java split
        
        NSLog(@"%@",words);