NSValueTranformer来加密数据 [英] NSValueTranformer to encrypt data
问题描述
我想在NSValueTransformer的帮助下加密一些核心数据列。这个想法是,我使用数据类型可变换,并为我的数据类型定义一些变换器。在转换方法内我想加密/解密的值。我定义了一个实际上什么都不做的变压器 - 加密项目目前没有实现。
I want to encrypt some core-data columns with help of an NSValueTransformer. The idea is, that I use data-type transformable and define some transformer for my datatypes. Inside the transformation-methods I want to encrypt/ decrypt the value. I defined a transformer that does actually nothing - the crypto-stuff is currently not implemented.
@implementation StringCryptoTransformer
+ (Class)transformedValueClass { return [NSString class]; }
+ (BOOL)allowsReverseTransformation { return YES; }
- (NSString*)transformedValue:(id)value {
NSLog(@"Transformer: %@",value);
if([value isKindOfClass:[NSString class]]){
return value;
}
return nil;
}
- (NSString*)reverseTransformedValue:(id)value
{
return value;
}
方法
- (NSString*)transformedValue:(id)value
获取调用的有效值,但是当获取对象时,我得到这个错误:
gets called with a valid value but when fetching objects I get this error:
* exception'NSInvalidArgumentException',reason:' - [__ NSCFString bytes]:
unrecognized selector sent to instance 0xf5859f0'
* Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[__NSCFString bytes]: unrecognized selector sent to instance 0xf5859f0'
有什么问题?
编辑:
到NSData,反之亦然。现在工作正常
I realized that I have to convert to NSData and vice versa. Now It works fine
- (id)transformedValue:(id)value {
NSData *data = [((NSString*)value) dataUsingEncoding:NSUTF8StringEncoding];
return [CryptoUtils encryptWithKey:self.key data:data];
}
- (id)reverseTransformedValue:(id)value
{
NSData *data = [CryptoUtils decryptWithKey:self.key data:value];
return [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
}
推荐答案
转换为 NSData
,反之亦然。现在工作正常
I realized that I have to convert to NSData
and vice versa. Now It works fine
- (id)transformedValue:(id)value {
NSData *data = [((NSString*)value) dataUsingEncoding:NSUTF8StringEncoding];
return [CryptoUtils encryptWithKey:self.key data:data];
}
- (id)reverseTransformedValue:(id)value
{
NSData *data = [CryptoUtils decryptWithKey:self.key data:value];
return [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
}
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