Objective-C 中Socket常用转换机制（NSData,NSString,int,Uint8,Uint16,Uint32,byte[]）

最近项目中要用到socket通讯，由于涉及到组包问题，所以需要数据类型之间的来回转换，现在分享出来

如果想要请教Socket的问题请留言，我会随时回答的

1. int类型转16进制hexstring

//int 转16进制
- (NSString *)hexFromInt:(NSInteger)val {
    return [NSString stringWithFormat:@"%X", val];
}

2.16进制转换为NSData

+ (NSData *)dataFromHexString:(NSString *)hexString
{
    NSAssert((hexString.length > 0) && (hexString.length % 2 == 0), @"hexString.length mod 2 != 0");
    NSMutableData *data = [[NSMutableData alloc] init];
    for (NSUInteger i=0; i<hexString.length; i+=2) {
        NSRange tempRange = NSMakeRange(i, 2);
        NSString *tempStr = [hexString substringWithRange:tempRange];
        NSScanner *scanner = [NSScanner scannerWithString:tempStr];
        unsigned int tempIntValue;
        [scanner scanHexInt:&tempIntValue];
        [data appendBytes:&tempIntValue length:1];
    }
    return data;
}

3.NSData转16进制

+ (NSString *)hexStringFromData:(NSData *)data
{
    NSAssert(data.length > 0, @"data.length <= 0");
    NSMutableString *hexString = [[NSMutableString alloc] init];
    const Byte *bytes = data.bytes;
    for (NSUInteger i=0; i<data.length; i++) {
        Byte value = bytes[i];
        Byte high = (value & 0xf0) >> 4;
        Byte low = value & 0xf;
        [hexString appendFormat:@"%x%x", high, low];
    }//for
    return hexString;
}

4.NSString转int类型

int a = [aStrinng  intValue];

5.uint8转NSData(占两位)

+ (NSData *)byteFromUInt8:(uint8_t)val
{
    NSMutableData *valData = [[NSMutableData alloc] init];

    unsigned char valChar[1];
    valChar[0] = 0xff & val;
    [valData appendBytes:valChar length:1];

    return [self dataWithReverse:valData];
}

6.uint16 转NSData（占四位）

+ (NSData *)bytesFromUInt16:(uint16_t)val
{
    NSMutableData *valData = [[NSMutableData alloc] init];

    unsigned char valChar[2];
    valChar[0] = 0xff & val;
    valChar[1] = (0xff00 & val) >> 8;
    [valData appendBytes:valChar length:2];

    return [self dataWithReverse:valData];
}

7.Uint32 转NSData（占八位）

+ (NSData *)bytesFromUInt32:(uint32_t)val
{
    NSMutableData *valData = [[NSMutableData alloc] init];

    unsigned char valChar[4];
    valChar[0] = 0xff & val;
    valChar[1] = (0xff00 & val) >> 8;
    valChar[2] = (0xff0000 & val) >> 16;
    valChar[3] = (0xff000000 & val) >> 24;
    [valData appendBytes:valChar length:4];

    return [self dataWithReverse:valData];
}

8.NSString 转NSData

NSData *data = [aString  dataUsingEncoding:NSUTF8StringEncoding];// 通过utf-8转为data

9.NSData转Uint8

+ (uint8_t)uint8FromBytes:(NSData *)fData
{
    NSAssert(fData.length == 1, @"uint8FromBytes: (data length != 1)");
    NSData *data = fData;
    uint8_t val = 0;
    [data getBytes:&val length:1];
    return val;
}

10.NSData转Uint16

+ (uint16_t)uint16FromBytes:(NSData *)fData
{
    NSAssert(fData.length == 2, @"uint16FromBytes: (data length != 2)");
    NSData *data = [self dataWithReverse:fData];;
    uint16_t val0 = 0;
    uint16_t val1 = 0;
    [data getBytes:&val0 range:NSMakeRange(0, 1)];
    [data getBytes:&val1 range:NSMakeRange(1, 1)];

    uint16_t dstVal = (val0 & 0xff) + ((val1 << 8) & 0xff00);
    return dstVal;
}

11.NSData转Uint32

+ (uint32_t)uint32FromBytes:(NSData *)fData
{
    NSAssert(fData.length == 4, @"uint32FromBytes: (data length != 4)");
    NSData *data = [self dataWithReverse:fData];

    uint32_t val0 = 0;
    uint32_t val1 = 0;
    uint32_t val2 = 0;
    uint32_t val3 = 0;
    [data getBytes:&val0 range:NSMakeRange(0, 1)];
    [data getBytes:&val1 range:NSMakeRange(1, 1)];
    [data getBytes:&val2 range:NSMakeRange(2, 1)];
    [data getBytes:&val3 range:NSMakeRange(3, 1)];

    uint32_t dstVal = (val0 & 0xff) + ((val1 << 8) & 0xff00) + ((val2 << 16) & 0xff0000) + ((val3 << 24) & 0xff000000);
    return dstVal;
}

12.NSData转Byte

uint8_t byteArray[[data length]];

 [data getBytes:&byteArray length:[data length]];


 for (int i = 0; i < [data length] ; i++ ) {
     Byte byte = byteArray[i];
     NSLog(@"--byte%x",byte);
 }

13.NSData的拼接

[data1 appendData:data2];

14.NSData转int (用CFSwapInt32BigToHost)

NSData *data4 = [completeData subdataWithRange:NSMakeRange(0, 4)];
int value = CFSwapInt32BigToHost(*(int*)([data4 bytes]));

以上可能会用到的反转字节序列代码

+ (NSData *)dataWithReverse:(NSData *)srcData
{
    //    NSMutableData *dstData = [[NSMutableData alloc] init];
    //    for (NSUInteger i=0; i<srcData.length; i++) {
    //        [dstData appendData:[srcData subdataWithRange:NSMakeRange(srcData.length-1-i, 1)]];
    //    }//for

    NSUInteger byteCount = srcData.length;
    NSMutableData *dstData = [[NSMutableData alloc] initWithData:srcData];
    NSUInteger halfLength = byteCount / 2;
    for (NSUInteger i=0; i<halfLength; i++) {
        NSRange begin = NSMakeRange(i, 1);
        NSRange end = NSMakeRange(byteCount - i - 1, 1);
        NSData *beginData = [srcData subdataWithRange:begin];
        NSData *endData = [srcData subdataWithRange:end];
        [dstData replaceBytesInRange:begin withBytes:endData.bytes];
        [dstData replaceBytesInRange:end withBytes:beginData.bytes];
    }//for

    return dstData;
}