OC NSData与NSString、UIImage、Byte

NSData与NSString的相互转换：

//将NSString转化为NSData
+(NSData *)toNSData:(NSString *)str{
    NSError *error = nil;
    NSData *aData = [str dataUsingEncoding:NSUTF8StringEncoding];
    if (aData.length && error ==nil) {
        return aData;
    }else{
        return nil;
    }
}
//将NSData转化为NSString
+(NSString *)transformData:(NSData *)data{
    NSError *error = nil;
    NSString *string = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
    if (string.length && error == nil) {
        return string;
    }else{
        return nil;
    }
}

NSData与UIImage的相互转换：

//将NSData转UIImage
UIImage *image = [UIImage imageWithData:data];

//将UIImage转NSData
NSData *data = UIImageJPEGRepresentation(image, 1.0);

NSData与字典或者数组的相互转换：

// 将字典或者数组转化为NSData
+ (NSData *)turnData:(id)theData
{
    NSError *error = nil;
    NSData *data = [NSJSONSerialization dataWithJSONObject:theData options:NSJSONWritingPrettyPrinted error:nil];

    if (data.length &&error== nil){
        return data;
    }else{
        return nil;
    }
}

// 将NSData转化为字典或者数组
+ (id)turnArrDic:(NSData *)data{

    NSError *error = nil;
    id object = [NSJSONSerialization JSONObjectWithData:data options:NSJSONReadingAllowFragments error:nil];

    if (object != nil && error == nil){
        return object;
    }else{
        // 解析错误
        return nil;
    }

}

NSData与 Byte数组的相互转换

//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++)
NSLog("testByte = %d\n",testByte[i]);

//Byte数组－> NSData
short int count = 7;
//int转2个字节
Byte byte2[2] = {(count>>8)&0xff,count&0xff};
NSData *adata2 = [[NSData alloc] initWithBytes:byte2 length:sizeof(byte2)];

NSDictionary 与 NSString 的相互转换

//NSDictionary 转 NSString
- (NSString*)dictionaryToJson:(NSDictionary *)dic
{
   NSError *parseError = nil;
   NSData  *jsonData = [NSJSONSerialization dataWithJSONObject:dic
                                                    options:NSJSONWritingPrettyPrinted
                                                      error:&parseError];

    return [[NSString alloc] initWithData:jsonData encoding:NSUTF8StringEncoding];

}

//NSString 转 NSDictionary 
+ (NSDictionary *)dictionaryWithJsonString:(NSString *)jsonString{
    if (jsonString == nil) {
        return nil;
    }
    NSData *jsonData = [jsonString dataUsingEncoding:NSUTF8StringEncoding];
    NSError *error;
    NSDictionary *dic = [NSJSONSerialization JSONObjectWithData:jsonData options:NSJSONReadingMutableContainers error:&error];
    if(error) {
        NSLog(@"json解析失败：%@",error);
        return nil;
    }
    return dic;
}

十六进制字符串转普通字符串

-(NSString *)stringFromHexString:(NSString *)hexString {
    char *myBuffer = (char *)malloc((int)[hexString length] / 2 + 1);
    bzero(myBuffer, [hexString length] / 2 + 1);
    for (int i = 0; i < [hexString length] - 1; i += 2) {
        unsigned int anInt;
        NSString * hexCharStr = [hexString substringWithRange:NSMakeRange(i, 2)];
        NSScanner * scanner = [[NSScanner alloc] initWithString:hexCharStr];
        [scanner scanHexInt:&anInt];
        myBuffer[i / 2] = (char)anInt;
    }
    NSString *unicodeString = [NSString stringWithCString:myBuffer encoding:4];
    return unicodeString;
}

NSData转十六进制字符串

-(NSString *) converDataToHexString:(NSData *)data
{
    if (data == nil) {
        return nil;
    }
    NSMutableString* hexString = [NSMutableString string];
    const unsigned char *p = [data bytes];
    for (int i=0; i < [data length]; i++) {
        [hexString appendFormat:@"%02x", *p++];
    }
    return hexString;
}