object inside NSMutableArray - ios

Question

I've a tableview which has list of images and image thumbnail (image list and thumbnails are parsed from JSON object), I'm adding image data objects to imagesArray like this -
ImageData *imageDataObject = [[ImageData alloc]initWithImageId:[[imageListArray
objectAtIndex:indexPath.row] imageId] imageData:imageData];
[imagesArray addObject:imageDataObject];
ImageData object
#property (nonatomic, strong) NSString* imageId;
#property (nonatomic, strong) NSData* imageData;
allImagesArray like this
[ImageData object1,ImageData object2,....]
I want to assign imageData of the object from this array based on selectedImageId to
UIImage* image =[[UIImage alloc] initWithData:........];
I'm not able to think of a way to get to that imageData based on selectedImageId
Please help.
Update -
Thank you all for the help, I could do it.

Answer 1

One of the possible way will be, iterate through the array, find your selectedImageId from the dictionary and use it.
Example:
ImageData *imageDataObject = nil;
for(int i=0; i<allImagesArray.count;i++){
NSDictionary *dict= allImagesArray[i];
imageDataObject = [dict objectForKey:selectedImageId];
if(imageDataObject != nil){
UIImage* image =[[UIImage alloc] initWithData:........];
//do whatever
break;
}
}
As per your EDIT:
What you have is an array of ImageData objects [ImageData1,ImageData2,...]. For each ImageData object, you have imageId and imageData property and what you want is simply compare the selectedImageId with this imageId and get the imageData from that.
So for that, in your PPImageViewController, you can iterate the allImagesArray like this and get the imageData.
for(ImageData* imgDataObj in self.allImagesArray){
if([imgDataObj.imageId isEqualToString:self.selectedImageId]){
UIImage* image =[[UIImage alloc] initWithData:imgDataObj.imageData];
}
}

Answer 2

So you have:
NSArray* allImagesArray = #[#{#"some_image_id_in_NSString_1":#"the data in NSData 1"}, #{#"some_image_id_in_NSString_2":#"the data in NSData 2"}];
As a property of PPImageViewController.
Assuming the imageid is an NSString and imagedata is NSData, you can create a method something like this on PPImageViewController:
- (UIImage*) findSelectedImage
{
UIImage* selectedImage;
for(NSDictionary* d in allImagesArray)
{
NSString* currentKey = [[d allKeys] objectAtIndex:0];
if([currentKey isEqualToString:[self selectedImageId]])
{
NSData* imageData = [d objectForKey:currentKey];
selectedImage = [UIImage imageWithData:imageData];
break;
}
}
return selectedImage;
}
Then call it like this, maybe on your viewDidLoad method:
UIImage* selectedImage = [self findSelectedImage];
Hope it help.

Answer 3

I see you are adding ImageData objects directly into the Array. You could have just used a NSDictionary instead. The key can be imageID (assuming it to be unique) and value will be the imageData object. Then pass the dictionary instead of array to PPImageViewController.
NSMutableDictionary *imageData = [NSMutableDictionary dictionary];
ImageData *imageDataObject = [[ImageData alloc]initWithImageId:[[imageListArray
objectAtIndex:indexPath.row] imageId] imageData:imageData];
[imageData setObject:imageDataObject forKey:imageId];
And then within PPImageViewController, you can easily get the imageDataObject based on selected imageID like this:
ImageData *imageDataObject = allImagesDictionary[selectedImageID];
EDIT:
NSArray *imageIndexes = [allImagesDictionary allKeys];
// Now use imageIndexes to populate your table. This will guarantee the order
// Fetch the imageId
selectedImageID = imageIndexes[indexPath.row];
// Fetch the imageData
ImageData *imageDataObject = allImagesDictionary[selectedImageID];