I am trying to save to and retrieve from NSMutableDictionary - ios

Question

Hello everyone !, I have an app that requires saving multiple Images. I want to save these images in a NSMutableDictionary as they may be accessed at another time..
I have a NSDictionaryFile class that looks like this set up as
#interface NSDictionaryFile : NSMutableDictionary
-(NSMutableDictionary *) mutDict {
mutDict = [[NSMutableDictionary alloc]initWithCapacity:24];
return mutDict;
}
-(void) addToDictionary : (NSData *) nsData : (NSString *) key {
NSString *tempStringKey = [NSString stringWithFormat:#"%#",key];
[mutDict setObject:[NSData dataWithData:nsData] forKey:tempStringKey];
NSLog(#"The Key is %# And The nsData has this %#",key,nsData);
}
-(NSData *) getFromDict : (NSData *) getNSData : (NSString *) getKey {
NSString *tempStringKey = [NSString stringWithFormat:#"%#",getKey];
NSData *tempData = [mutDict objectForKey:tempStringKey];
getNSData = [NSData dataWithData:tempData];
return getNSData;
}
I am saving to the above class from
#interface PhotoViewController : UIViewController<UIImagePickerControllerDelegate,UINavigationControllerDelegate>
-(void) imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info {
image = [info valueForKey:UIImagePickerControllerOriginalImage];
NSData *imgData = UIImagePNGRepresentation(image);
NSString *imageString;
num = 1;
imageString = [NSString stringWithFormat:#"imageKey%i",num];
[[NSDictionaryFile sharedDictionary] addToDictionary:imgData :imageString];
And I am retrieving it like this in the View Did Load like so,
-(void)viewDidLoad {
NSData *tempData;
NSData *imageData;
_num = 1;
imageString = [NSString stringWithFormat:#"imageKey%i",_num];
[[NSDictionaryFile sharedDictionary]getFromDict:tempData :imageString];
self.imageView.image = [UIImage imageWithData:imageData];
}
When the data is being saved to the NSDictionaryFie.m I know it is going because I am NSLog(#"The Image Data is %#",nsData); and my print out is , as would be expected.
89504e47 0d0a1a0a 0000000d 49484452 00000215 00000155 08020000 00d7368a d8000000 01735247 4200aece 1ce90000 001c6944 4f540000 00020000 00000000 00ab0000 00280000 00ab0000 00aa0003 41798433 c89e0000 40004944 41547801 a4bd079c 2547752f 7c677636 2a2192f1 b3fd6c63 3f6cb009 42486857 4802990c 1212b2c0 809f6d6c 30185bc0 27139456 bbda202d ca5aadb4 2badc2ae 36e79d0d b3333b39 e77c676e cef9debe b7730ef5 fed53d33 5a09f8de 07dffdd5 afe77475 d5a953a7
So , when the PickerdidFinisPicking , the image shows in my imageView, but when I try to retrieve it i get null.
If someone can tell me where I am going wrong it is much appreciated.
Regards
JZ

Answer 1

I think the error is pretty simple:
you are not using the return value from getFromDict, but an uninitialized variable imageData.
I think you should call your method and use the return value, like this
-(void)viewDidLoad {
NSData *tempData;
NSData *imageData;
_num = 1;
imageString = [NSString stringWithFormat:#"imageKey%i",_num];
imageData=[[NSDictionaryFile sharedDictionary]getFromDict:tempData :imageString];
self.imageView.image = [UIImage imageWithData:imageData];
}
Besides the getter methods seems overly complicated to me:
-(NSData *) getFromDict : (NSData *) getNSData : (NSString *) getKey {
NSString *tempStringKey = [NSString stringWithFormat:#"%#",getKey];
NSData *tempData = [mutDict objectForKey:tempStringKey];
getNSData = [NSData dataWithData:tempData];
return getNSData;
}
You pass the method an NSData which you just use to store a value and pass it back to the caller. It' useless to pass such a parameter.
Have you tried a slimmer method?
-(NSData *) getFromDict : (NSString *) getKey {
return[mutDict objectForKey:getKey];
}