NSData 与NSString,Byte数组，UIImage,int的相互转换

NSData 与 NSString，Byte数组，UIImage，int 的相互转换  

2012-08-10 09:35:47|  分类： ios_杂记|举报|字号 订阅

1. NSData 与 NSString
NSData－> NSString
NSString *aString = [[NSString alloc] initWithData:adataencoding:NSUTF8StringEncoding];
NSString－>NSData
NSString *aString = @"1234abcd";
NSData *aData = [aString dataUsingEncoding: NSUTF8StringEncoding];

2.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);

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&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);

3. NSData 与 UIImage
NSData－>UIImage
UIImage *aimage = [UIImage imageWithData: imageData];

//例：从本地文件沙盒中取图片并转换为NSData
NSString *path = [[NSBundle mainBundle] bundlePath];
NSString *name = [NSString stringWithFormat:@"ceshi.png"];
NSString *finalPath = [path stringByAppendingPathComponent:name];
NSData *imageData = [NSData dataWithContentsOfFile: finalPath];
UIImage *aimage = [UIImage imageWithData: imageData];

UIImage－> NSData
NSData *imageData = UIImagePNGRepresentation(aimae); 

4、NSData ->int 
NSString *str = [[NSString alloc]initWithData:data encoding:NSUTF8StringEncoding];
int number = [str intValue];

int ->NSData
int i =888;
NSString *aString = [NSString stringWithFormat:@"%d",i];
NSData *data = [aString dataUsingEncoding:NSUTF8StringEncoding];

5、NSData ->NSDictionary
在进行网络数据通信的时候，经常会遇到NSData类型的数据。在该数据是dictionary结构的情况下，系统没有提供现成的转换成 NSDictionary的方法，为此可以通过Category对NSDictionary进行扩展，以支持从NSData到NSDictionary的 转换。声明和实现如下：

@interface NSDictionary (Helpers)
+ (NSDictionary *)dictionaryWithContentsOfData:(NSData *)data;
@end

@implementation NSDictionary (Helpers)
+ (NSDictionary *)dictionaryWithContentsOfData:(NSData *)data {
    CFPropertyListRef plist =  CFPropertyListCreateFromXMLData(kCFAllocatorDefault, (CFDataRef)data,
                                                               kCFPropertyListImmutable,
                                                               NULL);
    if(plist == nil) return nil;
    if ([(id)plist isKindOfClass:[NSDictionary class]]) {
        return [(NSDictionary *)plist autorelease];
    }
    else {
        CFRelease(plist);
        return nil;
    }
}
@end