iOS-TCP/IP协议传输数据常用的类型转换(欢迎补充~)

之前一直在做关于TCP/IP的项目,关于数据处理是最麻烦的,每次遇到新的数据类型就多一个新类的方法,导致很混乱,今天决定整理下,形成一个分类.

写得不太好,有这方面经验的朋友可以在评论处留言,希望大家了一起完善~~~

NSData+Category.h

#import <Foundation/Foundation.h>

@interface NSData (Category)

// 注意:在NSData里面,<01>表示1个字节,用2个十六进制表示,1个十六进制表示4个bits

#pragma mark - valueMehthod

/// 返回包含8个字节Data，如:输入1 -> <00 00 00 00 00 00 00 01>
+ (instancetype)dataFromLong:(long)value ;
/// 返回包含4个字节Data，如:输入1 -> <00 00 00 01>
+ (instancetype)dataFromInt:(int)value ;
/// 返回包含2个字节Data，如:输入1 -> <00 01>
+ (instancetype)dataFromShort:(short)value ;
/// 返回包含1个字节Data，如:输入1 -> <01> value必须小于256
+ (instancetype)dataOneByteFromShort:(short)value ;

/// 返回long (必须满足:self.length >= 8)
- (long)longValue ;
/// 返回int (必须满足:self.length >= 4)
- (int)intValue ;
/// 返回short (必须满足:self.length >= 2)
- (short)shortValue ;
/// 返回short (必须满足:self.length >= 1)
- (short)shortValueFromOneByteData ;


#pragma mark - StringMethod

/// 返回Data <01ff> -> "01ff" 如果传入参数 str 为 1ff, 则hexdata打印出:hexdata: <01ff>
+ (instancetype)hexDataFromHexString:(NSString *)hexString ;
/// 十六进制字符串 <01ff> -> "01ff"
+ (NSString *)hexStringFromHexData:(NSData *)hexData ;

/// 返回网络字节序的Data IPString -> data
+ (instancetype)ipDataFromIpString:(NSString *)ipString ;
/// ip字符串
+ (NSString *)ipStringFromIpData:(NSData *)ipData ;

/// 小端大端反转 (原本是小端,则变成大端;反之亦然)
- (NSData *)reverseBitAndLittleEnd ;

@end

NSData+Category.m

#import "NSData+Category.h"
#import <arpa/inet.h>

@implementation NSData (Category)

#pragma mark -- valueMethod

+ (instancetype)dataFromLong:(long)value {
    return [NSMutableData dataWithBytes: &value length: sizeof(long)];
}

+ (instancetype)dataFromInt:(int)value {
    return [NSMutableData dataWithBytes: &value length: sizeof(int)];
}

+ (instancetype)dataFromShort:(short)value {
    return [NSMutableData dataWithBytes: &value length: sizeof(short)];
}

+ (instancetype)dataOneByteFromShort:(short)value {
    NSAssert(value <= 256-1, @"value must be not overflow one byte value");
    return [NSMutableData dataWithBytes: &value length: sizeof(short)-1];
}

- (long)longValue {
    NSAssert(self.length >= 8, @"data length must be bigger than 8");
    long value;
    [self getBytes: &value length: sizeof(long)];
    return value;
}

- (int)intValue {
    NSAssert(self.length >= 4, @"data length must be bigger than 4");
    int value;
    [self getBytes: &value length: sizeof(int)];
    return value;
}

- (short)shortValue {
    NSAssert(self.length >= 2, @"data length must be bigger than 2");
    short value;
    [self getBytes: &value length: sizeof(short)];
    return value;
}

- (short)shortValueFromOneByteData {
    NSAssert(self.length >= 1, @"data length must be bigger than 1");
    short value;
    [self getBytes: &value length: 1];
    return value;
}

#pragma Mark - stringMethod
/// 返回Data <01ff> -> "01ff" 如果传入参数 str 为 1ff, 则hexdata打印出:hexdata: <01ff>
+ (instancetype)hexDataFromHexString:(NSString *)hexString {
    if (!hexString || [hexString length] == 0)  return nil;
    
    NSMutableData *hexData = [[NSMutableData alloc] initWithCapacity:8];
    NSRange range;
    if ([hexString length] % 2 == 0) {
        range = NSMakeRange(0, 2);
    } else {
        range = NSMakeRange(0, 1);
    }
    for (NSInteger i = range.location; i < [hexString length]; i += 2) {
        unsigned int anInt;
        NSString *hexCharStr = [hexString substringWithRange:range];
        NSScanner *scanner = [[NSScanner alloc] initWithString:hexCharStr];
        
        [scanner scanHexInt:&anInt];
        NSData *entity = [[NSData alloc] initWithBytes:&anInt length:1];
        [hexData appendData:entity];
        
        range.location += range.length;
        range.length = 2;
    }
    return hexData;
}

/// 十六进制字符串 <01ff> -> "01ff"
+ (NSString *)hexStringFromHexData:(NSData *)hexData {
    if (!hexData || [hexData length] == 0) return @"";
    
    NSMutableString *string = [[NSMutableString alloc] initWithCapacity:[hexData length]];
    
    [hexData enumerateByteRangesUsingBlock:^(const void *bytes, NSRange byteRange, BOOL *stop) {
        unsigned char *dataBytes = (unsigned char*)bytes;
        for (NSInteger i = 0; i < byteRange.length; i++) {
            NSString *hexStr = [NSString stringWithFormat:@"%x", (dataBytes[i]) & 0xff];
            if ([hexStr length] == 2) {
                [string appendString:hexStr];
            } else {
                [string appendFormat:@"0%@", hexStr];
            }
        }
    }];
    
    return string;
}

/// 返回网络字节序的Data IPString -> data
+ (instancetype)ipDataFromIpString:(NSString *)ipString {
    unsigned int s_addr = inet_addr([ipString UTF8String]);
    NSData *data = [NSMutableData dataWithBytes: &s_addr length: sizeof(unsigned int)];
    return data.reverseBitAndLittleEnd;
}

/// ip字符串
+ (NSString *)ipStringFromIpData:(NSData *)ipData {
    /// to unsigned int
    unsigned int value = *(unsigned int *)ipData.reverseBitAndLittleEnd.bytes;
    
    /// to char
    struct in_addr addr;
    addr.s_addr = value;
    char *strAddr = inet_ntoa(addr);
    
    return [NSString stringWithUTF8String:strAddr];
}

/// 小端大端反转 (原本是小端,则变成大端;反之亦然)
- (NSData *)reverseBitAndLittleEnd {
    NSMutableData *littleEndData = [NSMutableData data];
    
    for(int i = 0; i < self.length; i++){
        NSData *subdata = [self subdataWithRange:NSMakeRange(self.length -i -1, 1)];
        [littleEndData appendData:subdata];
    }
    return littleEndData;
}
@end