OC系统类型各种转换

#pragma mark - //字符串->数组 && 数组->字符串

+ (NSString *)stringbyReversString:(NSString *)string{
    //定义一个空的可变字符串
    NSMutableString *str = [NSMutableString string];
    //给每个字符后面加一个字符
    for (int i = 0; i < string.length; i ++) {
        char ch = [string characterAtIndex:i];
        [str appendFormat:@"%c-",ch];
    }
    //删除最后一个字符
    [str deleteCharactersInRange:NSMakeRange(str.length - 1,1)];
    //将字符串添加到数组中
    NSArray *array = [str componentsSeparatedByString:@"-"];
    NSMutableArray *mutablearray = [NSMutableArray array];
    [mutablearray addObjectsFromArray:array];
    //改变数组，倒置！！！（随便怎么改变就在这里改变）
    //---------------------------
    [mutablearray exchangeObjectAtIndex:0 withObjectAtIndex:array.count - 1];
    //---------------------------
    //将数组转换为字符串
    NSMutableString *str1 = [NSMutableString string];
    for (id object in mutablearray){
        [str1 appendFormat:@"%@",object];
    }
    return str1;
}

#pragma mark - 字符串和数组的互相转换
    //字符串 -> 数组
    NSString *string = [NSString stringWithFormat:@"101010-1021s-ad30-2132ada38-13221-1"];
    NSArray *array = [string componentsSeparatedByString:@"-"];
    NSLog(@"%@",array);
    //数组 -> 字符串
    NSMutableString *newstring = [NSMutableString string];
    for (id object in array){
        NSLog(@"%@",object);
        [newstring appendFormat:@"%@",object];
    }
    NSLog(@"%@",newstring);
    
#pragma mark - 字符串和NSNumber的互相转换    
    NSNumber *number2 = @12213123;
    NSNumberFormatter *fomatter = [[NSNumberFormatter alloc]init];
    //    [fomatter setNumberStyle:NSNumberFormatterSpellOutStyle];
    NSString *string2 = [fomatter stringFromNumber:number2];
    NSNumber *number20 = [fomatter numberFromString:string2];
    NSLog(@"%@",number20);
    NSLog(@"%@",string2);
    
    NSString *string3 = @"111";
    NSNumber *number3 = [NSNumber numberWithInt:[string3 intValue]];
    NSLog(@"%@",number3);
    [fomatter release];
}

    //字符串->数组->字符串
    NSString *str1 = @"one,two,three";
    NSArray *array = [str1 componentsSeparatedByString:@","];
    NSString *str2 = [array componentsJoinedByString:@"-"];
    NSLog(@"%@",str2);

        //NSDate -> NSString
        NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
        
        //设定时间格式,这里可以设置成自己需要的格式
        
        [dateFormatter setDateFormat:@"yyyy年MM月dd日 HH:mm:ss"];

        NSDate *date = [NSDate dateWithTimeIntervalSinceNow:0];
        
        NSString *currentDateStr = [dateFormatter stringFromDate:date];
        //输出格式为：2014年12月22日 13:48:52
        
        NSLog(@"%@",currentDateStr);

        //NSString ->NSDate
        NSString *string = [NSString stringWithFormat:@"19931003"];
        NSDateFormatter *fomatter = [[NSDateFormatter alloc]init];
        [fomatter setTimeZone:[NSTimeZone timeZoneForSecondsFromGMT:8]];
        [fomatter setDateFormat:@"yyyyMMdd"];
        NSDate *date = [fomatter dateFromString:string];
        NSLog(@"%@",date);