Try to use
NSData *imgData = [NSData dataWithContentsOfFile:imgPath];
UIImage *thumbNail = [[UIImage alloc] initWithData:imgData];
or
NSData *imgData = [[NSData alloc] initWithContentsOfURL:[NSURL fileURLWithPath:imgPath]];
UIImage *thumbNail = [[UIImage alloc] initWithData:imgData];