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

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1. //int 转16进制
2. - (NSString *)hexFromInt:(NSInteger)val {
3. return [NSString stringWithFormat:@"%X", val];
4. }

2.16进制转换为NSData

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1. + (NSData *)dataFromHexString:(NSString *)hexString
2. {
3. NSAssert((hexString.length > 0) && (hexString.length % 2 == 0), @"hexString.length mod 2 != 0");
4. NSMutableData *data = [[NSMutableData alloc] init];
5. for (NSUInteger i=0; i<hexString.length; i+=2) {
6. NSRange tempRange = NSMakeRange(i, 2);
7. NSString *tempStr = [hexString substringWithRange:tempRange];
8. NSScanner *scanner = [NSScanner scannerWithString:tempStr];
9. unsigned int tempIntValue;
10. [scanner scanHexInt:&tempIntValue];
11. [data appendBytes:&tempIntValue length:1];
12. }
13. return data;
14. }

3.NSData转16进制

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1. + (NSString *)hexStringFromData:(NSData *)data
2. {
3. NSAssert(data.length > 0, @"data.length <= 0");
4. NSMutableString *hexString = [[NSMutableString alloc] init];
5. const Byte *bytes = data.bytes;
6. for (NSUInteger i=0; i<data.length; i++) {
7. Byte value = bytes[i];
8. Byte high = (value & 0xf0) >> 4;
9. Byte low = value & 0xf;
10. [hexString appendFormat:@"%x%x", high, low];
11. }//for
12. return hexString;
13. }

4.NSString转int类型

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1. int a = [aStrinng intValue];

5.uint8转NSData(占两位)

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1. + (NSData *)byteFromUInt8:(uint8_t)val
2. {
3. NSMutableData *valData = [[NSMutableData alloc] init];
4. unsigned char valChar[1];
5. valChar[0] = 0xff & val;
6. [valData appendBytes:valChar length:1];
7. return [self dataWithReverse:valData];
8. }

6.uint16 转NSData（占四位）

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1. + (NSData *)bytesFromUInt16:(uint16_t)val
2. {
3. NSMutableData *valData = [[NSMutableData alloc] init];
4. unsigned char valChar[2];
5. valChar[0] = 0xff & val;
6. valChar[1] = (0xff00 & val) >> 8;
7. [valData appendBytes:valChar length:2];
8. return [self dataWithReverse:valData];
9. }

7.Uint32 转NSData（占八位）

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1. + (NSData *)bytesFromUInt32:(uint32_t)val
2. {
3. NSMutableData *valData = [[NSMutableData alloc] init];
4. unsigned char valChar[4];
5. valChar[0] = 0xff & val;
6. valChar[1] = (0xff00 & val) >> 8;
7. valChar[2] = (0xff0000 & val) >> 16;
8. valChar[3] = (0xff000000 & val) >> 24;
9. [valData appendBytes:valChar length:4];
10. return [self dataWithReverse:valData];
11. }

8.NSString 转NSData

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

9.NSData转Uint8

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1. + (uint8_t)uint8FromBytes:(NSData *)fData
2. {
3. NSAssert(fData.length == 1, @"uint8FromBytes: (data length != 1)");
4. NSData *data = fData;
5. uint8_t val = 0;
6. [data getBytes:&val length:1];
7. return val;
8. }

10.NSData转Uint16

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1. + (uint16_t)uint16FromBytes:(NSData *)fData
2. {
3. NSAssert(fData.length == 2, @"uint16FromBytes: (data length != 2)");
4. NSData *data = [self dataWithReverse:fData];;
5. uint16_t val0 = 0;
6. uint16_t val1 = 0;
7. [data getBytes:&val0 range:NSMakeRange(0, 1)];
8. [data getBytes:&val1 range:NSMakeRange(1, 1)];
9. uint16_t dstVal = (val0 & 0xff) + ((val1 << 8) & 0xff00);
10. return dstVal;
11. }

11.NSData转Uint32

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1. + (uint32_t)uint32FromBytes:(NSData *)fData
2. {
3. NSAssert(fData.length == 4, @"uint32FromBytes: (data length != 4)");
4. NSData *data = [self dataWithReverse:fData];
5. uint32_t val0 = 0;
6. uint32_t val1 = 0;
7. uint32_t val2 = 0;
8. uint32_t val3 = 0;
9. [data getBytes:&val0 range:NSMakeRange(0, 1)];
10. [data getBytes:&val1 range:NSMakeRange(1, 1)];
11. [data getBytes:&val2 range:NSMakeRange(2, 1)];
12. [data getBytes:&val3 range:NSMakeRange(3, 1)];
13. uint32_t dstVal = (val0 & 0xff) + ((val1 << 8) & 0xff00) + ((val2 << 16) & 0xff0000) + ((val3 << 24) & 0xff000000);
14. return dstVal;
15. }

12.NSData转Byte

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1. uint8_t byteArray[[data length]];
2. [data getBytes:&byteArray length:[data length]];
3. for (int i = 0; i < [data length] ; i++ ) {
4. Byte byte = byteArray[i];
5. NSLog(@"--byte%x",byte);
6. }

13.NSData的拼接

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1. [data1 appendData:data2];

14.NSData转int (用CFSwapInt32BigToHost)

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

以上可能会用到的反转字节序列代码

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1. + (NSData *)dataWithReverse:(NSData *)srcData
2. {
3. // NSMutableData *dstData = [[NSMutableData alloc] init];
4. // for (NSUInteger i=0; i<srcData.length; i++) {
5. // [dstData appendData:[srcData subdataWithRange:NSMakeRange(srcData.length-1-i, 1)]];
6. // }//for
7. NSUInteger byteCount = srcData.length;
8. NSMutableData *dstData = [[NSMutableData alloc] initWithData:srcData];
9. NSUInteger halfLength = byteCount / 2;
10. for (NSUInteger i=0; i<halfLength; i++) {
11. NSRange begin = NSMakeRange(i, 1);
12. NSRange end = NSMakeRange(byteCount - i - 1, 1);
13. NSData *beginData = [srcData subdataWithRange:begin];
14. NSData *endData = [srcData subdataWithRange:end];
15. [dstData replaceBytesInRange:begin withBytes:endData.bytes];
16. [dstData replaceBytesInRange:end withBytes:beginData.bytes];
17. }//for
18. return dstData;
19. }