这是我的PictureDataTransformer.m#import"PictureDataTransformer.h"@implementationPictureDataTransformer+(Class)transformedValueClass{return[NSDataclass];}+(BOOL)allowsReverseTransformation{returnYES;}-(id)transformedValue:(id)value{returnUIImagePNGRepresetation(value);}错误函数“UIImagePNGRepresetation”的隐