display images from address book

I am using collection view ,when i click last item it is going to address book, after that if i select any contacts details ,i want to get contact person name,number and image

for image i am writing the code like this UIImage *img ;

if (person != nil && ABPersonHasImageData(person)) {
    if ((&ABPersonCopyImageDataWithFormat) != nil ) {

        img= [UIImage imageWithData:(__bridge NSData *)ABPersonCopyImageDataWithFormat(person, kABPersonImageFormatThumbnail)];
    }

} else {

    NSString *imageUrlString = @"http://ift.tt/1ybakcH";
    NSURL *url = [NSURL URLWithString:imageUrlString];
    NSData *data = [[NSData alloc] initWithContentsOfURL:url];
    img= [UIImage imageWithData:data];

} 

string =[NSString stringWithFormat:@"%@",img]; [self.imageArray insertObject:string atIndex:0];

after that i am giving image array to collection view cell

cell.image.image=[UIImage imageNamed:[self.imageArray objectAtIndex:indexPath.row]];

but it is not displaying any image when i give defaults image like image.jpeg it was displaying , that reason i am printing img from address book it use showing UIImage:0X7a7ad00 in that format. how can i get image.png format from UIImage: 0x7a7ad700 , or how can i display images in cell from nsdata