操纵数组内容

#import <Foundation/Foundation.h>int main(int argc, const char * argv[]){    @autoreleasepool {                NSMutableArray *listOfNames = [[NSMutableArray alloc] init];                [listOfNames addObject:@"Jack"];        [listOfNames addObject:@"Cindy"];        [listOfNames addObject:@"Lucy"];                NSLog(@"OBJECTS ADDED TO ARRAY: %@", listOfNames);        // 在1号索引处插入 @“Cook” 原先在此处的元素后移，索引数变为2        [listOfNames insertObject:@"Cook" atIndex:1];        NSLog(@"AFTER INSERTING, THE ARRAY: %@", listOfNames);        // 把3号索引处的对象替换成 @“Jim”        [listOfNames replaceObjectAtIndex:3 withObject:@"Jim"];        NSLog(@"AFTER'Lucy' REPLACED BY 'Jim', THE ARRAY IS %@", listOfNames);        // 把0号和1号处的索引对象进行换位        [listOfNames exchangeObjectAtIndex:0 withObjectAtIndex:1];        NSLog(@"OBJECT AT INDEX 0 EXCHANGED WITH OBJECT AT INDEX 1 IN ARRAY: %@",listOfNames);        // 移除指定的对象        [listOfNames removeObject:@"Jack"];        NSLog(@"THE ARRAY: %@", listOfNames);        // 移除数组最后一个对象        [listOfNames removeLastObject];        NSLog(@"THE ARRAY: %@", listOfNames);        // 移除数组中的使用对象        [listOfNames removeAllObjects];        NSLog(@"THE ARRAY: %@", listOfNames);                  }    return 0;}