In your example, you have things in some reverse order. Installation UIImage *logoImageshould be the last part. In addition, turning a URL into an image is a two-step process.
First you need to get the data:
NSString *filename = @"12121212";
NSURL *tempURL = [NSURL URLWithString:[NSString stringWithFormat:@"http://www.example.com/devlopment.cfm?method=%@",fileName]];
NSData *tempData = [NSData dataWithContentsOfUrl:tempURL];
:
UIImage *logoImage = [UIImage imageWithData:tempData];
, , , .