NSData，NSImage,NSDictionary,NSString，NSInteger，Float，NSURL 等等互相转换

一：NSString和NSURL 转换

//NSString->NSURLNSString *urlString=[@"http://www.google.com" stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding];NSURL *url=[NSURL URLWithString:urlString]; //NSURL->NSString NSString *urlString=[[url absoluteString] stringByReplacingPercentEscapesUsingEncoding:NSUTF8StringEncoding];

二：NSString和NSData转换（即可作json串互相转换）

//NSData－> NSStringNSString *testString = [[NSString alloc] initWithData:testData encoding:NSUTF8StringEncoding];//NSString－>NSDataNSString *aString = @"我是NSString";NSData *testData = [testString dataUsingEncoding: NSUTF8StringEncoding];

三：NSData和NSImage转换

//NSData－>UIImageUIImage *testImage = [UIImage imageWithData: imageData];//UIImage->NSDataNSData *imageData = UIImagePNGRepresentation(testImage)//或者NSData *imageData = UIImageJPEGRepresentation(testImage,1.0)

四：NSData和NSDictionary转换

//NSData-->NSDictionaryNSDictionary *testDict = [NSJSONSerialization JSONObjectWithData:testData options:NSJSONReadingMutableContainers error:nil]//或者NSKeyedUnarchiver *unarchiver = [[NSKeyedUnarchiver alloc] initForReadingWithData:testData];  NSDictionary *myDictionary = [[unarchiver decodeObjectForKey:@"Some Key Value"] retain];  [unarchiver finishDecoding];//NSDictionay --> NSDataNSMutableData *data = [[NSMutableData alloc] init];  NSKeyedArchiver *archiver = [[NSKeyedArchiver alloc] initForWritingWithMutableData:data];  [archiver encodeObject:params forKey:@"Some Key Value"];  [archiver finishEncoding];

五：NSDictionary和JSON转换

//NSDictionary -> JSON:  //这个方法是SBJson类库里的，需要导入SBJson.hNSString *jsonStr=[dict JSONRepresentation];//或者原生类库中NSData      *data = [NSJSONSerialization dataWithJSONObject:dict options:NSJSONWritingPrettyPrinted error:nil];NSString    *string = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];//建议（特别是http取回来的jsonStr转换如下）//JSON->NSDictionary:NSData *jsonData = [testJsonStr dataUsingEncoding:NSUTF8StringEncoding];NSDictionary *dict = [NSJSONSerialization JSONObjectWithData:jsonData options:NSJSONReadingMutableContainers error:nil]

//摘录其他同学的

NSData 与 Byte
NSData－> Byte数组
NSString *testString = @"1234567890";
NSData *testData = [testString dataUsingEncoding: NSUTF8StringEncoding];
Byte *testByte = (Byte *)[testData bytes];
for(int i=0;i<[testData length];i++)
printf("testByte = %d\n",testByte[i]);

Byte数组－> NSData
Byte byte[] = {0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23};
NSData *adata = [[NSData alloc] initWithBytes:byte length:24];

Byte数组－>16进制数
Byte *bytes = (Byte *)[aData bytes];
NSString *hexStr=@"";
for(int i=0;i<[encryData length];i++)
{
NSString *newHexStr = [NSString stringWithFormat:@"%x",bytes[i]&0xff]; ///16进制数
if([newHexStr length]==1)
hexStr = [NSString stringWithFormat:@"%@0%@",hexStr,newHexStr];
else
hexStr = [NSString stringWithFormat:@"%@%@",hexStr,newHexStr];
}
NSLog(@"bytes 的16进制数为:%@",hexStr);

16进制数－>Byte数组
///// 将16进制数据转化成Byte 数组
NSString *hexString = @"3e435fab9c34891f"; //16进制字符串
int j=0;
Byte bytes[128]; 

 ///3ds key的Byte 数组， 128位
for(int i=0;i<[hexString length];i++)
{
int int_ch;  /// 两位16进制数转化后的10进制数
 
unichar hex_char1 = [hexString characterAtIndex:i]; ////两位16进制数中的第一位(高位*16)
int int_ch1;
if(hex_char1 >= '0' && hex_char1 <='9')
int_ch1 = (hex_char1-48)*16;   //// 0 的Ascll - 48
else if(hex_char1 >= 'A' && hex_char1 <='F')
int_ch1 = (hex_char1-55)*16; //// A 的Ascll - 65
else
int_ch1 = (hex_char1-87)*16; //// a 的Ascll - 97
i++;
 
unichar hex_char2 = [hexString characterAtIndex:i]; ///两位16进制数中的第二位(低位)
int int_ch2;
if(hex_char2 >= '0' && hex_char2 <='9')
int_ch2 = (hex_char2-48); //// 0 的Ascll - 48
else if(hex_char1 >= 'A' && hex_char1 <='F')
int_ch2 = hex_char2-55; //// A 的Ascll - 65
else
int_ch2 = hex_char2-87; //// a 的Ascll - 97
 
int_ch = int_ch1+int_ch2;
NSLog(@"int_ch=%d",int_ch);
bytes[j] = int_ch;  ///将转化后的数放入Byte数组里
j++;
}
NSData *newData = [[NSData alloc] initWithBytes:bytes length:128];
NSLog(@"newData=%@",newData);