ios开发－数据类型转换

ios开发－数据类型转换－－个人学习之路的总结

1，NSData 与 NSString
　　NSData --> NSString
　　NSString*aString = [[NSString alloc] initWithData:adata encoding:NSUTF8StringEncoding];
　　NSString --> NSData
　　NSString*aString = @"1234";
　　NSData*aData = [aString dataUsingEncoding: NSUTF8StringEncoding];
 
2，NSData 与 Byte
　　
     NSData --> Byte
　
　  NSString*testString = @"1234567890";

     NSData *testData = [testString  dataUsingEncoding: NSUTF8StringEncoding];
　
     Byte *testByte = (Byte *)[testData bytes];

     Byte --> 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);
 
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 与 NSMutableData
　　NSData --> MSMutableData
　　NSData*data=[[NSData alloc]init];
　　NSMutableData*mdata=[[NSMutableData alloc]init];   
       mdata=[NSDatadataWithData:data];

 

5.NSDictionary类型转换为NSData类型：
系统方法
+ (NSData *)dataWithJSONObject:(id)obj options:(NSJSONWritingOptions)opt error:(NSError **)error;

//NSDictionary -> NSData:
 NSDictionary *params = [NSDictionarydictionaryWithObjectsAndKeys: @"balance", @"key", @"remaining balance",@"label",  @"45", @"value",   @"USD", @"currencyCode",nil];        
   NSMutableData *data =[[NSMutableData alloc] init];
 NSKeyedArchiver *archiver = [[NSKeyedArchiveralloc] initForWritingWithMutableData:data];
 [archiver encodeObject:paramsforKey:@"Some Key Value"];
 [archiver finishEncoding];
 
6.NSData类型转换为NSDictionary类型：
//NSData -> NSDictionary
 NSData *data = [[NSMutableData alloc]initWithContentsOfFile:[self dataFilePath]];
 NSKeyedUnarchiver *unarchiver =[[NSKeyedUnarchiver alloc] initForReadingWithData:data];
 NSDictionary *myDictionary = [[unarchiverdecodeObjectForKey:@"Some Key Value"] retain];
[unarchiver finishDecoding];[unarchiver release];
 [data release];
 

7: NSData NSArray 转换

  NSArray *arr1= [[NSArray alloc]initWithObjects:@"0",@"5",nil];

    NSData *data= [NSKeyedArchiver archivedDataWithRootObject:arr1];

    NSArray *arr2= [NSKeyedUnarchiver unarchiveObjectWithData:data];

    NSLog(@"->%@",[arr1 objectAtIndex:1]);

    NSLog(@"->%@",[arr2 objectAtIndex:1]);