Fatal error when setting UIImageView in objective c - ios

Question

Hello i have a UIImageview and trying to set the image which was previously saved in a NSArray and then the NSArray is saved into an NSMutableDictionary. Here is the error and the code. Any help appreciated.
*** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[__NSCFConstantString _isSymbolImage]: unrecognized selector sent to instance 0x100e14318'
terminating with uncaught exception of type NSException
myAppDelegate *appDelegate = (myAppDelegate *)[UIApplication sharedApplication].delegate;
NSMutableArray *allKeys = [[appDelegate.localDataForIngestAndErrorVideos allKeys] mutableCopy];
for (NSString *key in allKeys) {
NSArray *object = (NSArray*)[appDelegate.localDataForIngestAndErrorVideos objectForKey:key];
NSLog(#"id object ingest: %#",[object objectAtIndex:0]);
if ( [cell.Model.ContentItem.videoUploadStatus isEqualToString:#"ingest"])
{
cell.Model.ContentItem.mediaVideoUriHls = (NSURL*)[object objectAtIndex:2];
UIImage *tempImage = [[UIImage alloc]init];
tempImage = [object objectAtIndex:1];
[cell.mediaImageView setImage:tempImage]; <=== here crashes
}
}

Answer 1

The error [__NSCFConstantString _isSymbolImage]: unrecognized selector sent to instance is saying this:
Let's translate first: __NSCFConstantString is a inner (optimized) class for NSString, so just consider it as NSString
So you have NSString instance and you try to call _isSymbolImage method on it. That method is hidden, it's an under the hood call from iOS SDK.
But that method doesn't exists on NSString, it doesn't know it, hence the error you are getting.
Seeing the crash line:
[cell.mediaImageView setImage:tempImage];
The inner method called makes sense, you are treating tempImage as it were an UIImage.
So [object objectAtIndex:1] is a NSString not a UIImage.
Now, I'd suggest to use custom model for your NSDictionary appDelegate.localDataForIngestAndErrorVideos. It's better than handling NSArray/NSDictionary without knowing what's inside it each time.
You could also add to it methods/compute properties like -(NSURL)ingestURL, etc to make your code easier and more readable.
Side note:
UIImage *tempImage = [[UIImage alloc]init];
tempImage = [object objectAtIndex:1];
The alloc/init is useless, since you are setting the value. You are doing an alloc/init for nothing, since you are ignoring it just after.