UIImage (from path) to NSData causes crash

Question

I have following code

for (int i=0; i<self.imageArray.count; i++) 
{
    [self.operation addData:[self getDataFromImage:[self.imageArray objectAtIndex:i]] 
    forKey:[NSString stringWithFormat:@"pa_image%d",i+1] 
    mimeType:@"image/png" 
    fileName:[NSString stringWithFormat:@"pa_image%d.png",i+1]];

}

From here following method is calling

-(NSData *)getDataFromImage:(UIImage *)image
{
    NSData *imageData=  UIImageJPEGRepresentation(image, 0.1);
    return imageData;
}

There are 2 scenarios in my code for imageArray when

1) values are coming from API in imageArray like "images/upload/d872f1.png", "images/upload/0fdade.png" then returning nil in NSData. I want to convert from this path to NSData. how to Do?

After executing this line my app is crashing. It is giving

Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[__NSCFString CGImage]: unrecognized selector sent to instance 0x7f83a1f13510'

2) When i am uploading from phone its like " , {834, 1250} ”.My code is working properly in this scenario its converting into NSData.

For more details here is my addData method

-(void) addData:(NSData*) data forKey:(NSString*) key mimeType:(NSString*) mimeType fileName:(NSString*) fileName 
 {

  if ([self.request.HTTPMethod isEqualToString:@"GET"]) 
  {
  [self.request setHTTPMethod:@"POST"];
 }

 NSDictionary *dict = @{@"data": data,
@"name": key,
@"mimetype": mimeType,
@"filename": fileName};

[self.dataToBePosted addObject:dict];
}

Answer 1

        if([[self.imageArray objectAtIndex:i] isKindOfClass:[NSString class]])
        {

            NSString *stringFromAPI = [self.imageArray objectAtIndex:i];

            NSURL *url=[NSURL URLWithString:stringFromAPI];

            image = [UIImage imageWithData:[NSData dataWithContentsOfURL:url]];

        }else
        {
            image = [self.imageArray objectAtIndex:i];
        }
        [self.operation addData:[self getDataFromImage:image]
                         forKey:[NSString stringWithFormat:@"pa_image%d",i+1]
                       mimeType:@"image/png"
                       fileName:[NSString stringWithFormat:@"pa_image%d.png",i+1]];