OC 字符串与数组互转

    NSMutableArray *array =@[@"111",@"4444",@"33333"].mutableCopy;
    
    // 数组转字符串
    NSString *str = [array componentsJoinedByString:@","];
    NSLog(@"%@",str);
    
    // 字符串转数组
    NSArray * ar = [str componentsSeparatedByString:@","];
    NSLog(@"%@",ar);