代码清单18-2 数组操作

NSMutableArray *dataArray = [NSMutableArray arrayWithObjects:
            [NSMutableString stringWithString: @"one"],
            [NSMutableString stringWithString: @"two"],
            [NSMutableString stringWithString: @"three"],
            Nil
        ];
        NSMutableArray *dataArray2;
        NSMutableString *mStr;
        
        NSLog(@"dataArray: ");
        for(NSString *elem in dataArray)
            NSLog(@"   %@", elem);
        
        //复制一份，然后删除副本的第一个元素
        dataArray2 = [dataArray mutableCopy];
        mStr = [dataArray objectAtIndex: 0];
        [mStr appendString: @"ONE"];
        
        NSLog(@"dataArray:   ");
        for(NSString *elem in dataArray)
            NSLog(@"   %@", elem);
        
        NSLog(@"dataArray2:   ");
        for(NSString *elem in dataArray2)
            NSLog(@"   %@", elem);

2013-11-14 20:43:20.248 prog2[3503:303] dataArray: 

2013-11-14 20:43:20.249 prog2[3503:303]    one

2013-11-14 20:43:20.249 prog2[3503:303]    two

2013-11-14 20:43:20.250 prog2[3503:303]    three

2013-11-14 20:43:20.250 prog2[3503:303] dataArray:   

2013-11-14 20:43:20.250 prog2[3503:303]    oneONE

2013-11-14 20:43:20.250 prog2[3503:303]    two

2013-11-14 20:43:20.250 prog2[3503:303]    three

2013-11-14 20:43:20.251 prog2[3503:303] dataArray2:   

2013-11-14 20:43:20.251 prog2[3503:303]    oneONE

2013-11-14 20:43:20.251 prog2[3503:303]    two

2013-11-14 20:43:20.251 prog2[3503:303]    three