new enemies appearing with each level

Lines like this are not changing the value stored in the variable

level + 1;

You need to change these lines to be either:

level = level + 1;

or

level++;

The same goes for any line where you are trying to increment a variable

Example code to rotate an image in a UIImageView

UIImage *image = [UIImage imageNamed:@"image.png"];
UIImageView *imageView = [ [ UIImageView alloc ] initWithFrame:CGRectMake(0.0, 0.0,     image.size.width, image.size.height) ];
imageView.image = image;
[self addSubview:imageView];
CGAffineTransform rotate = CGAffineTransformMakeRotation( 1.0 / 180.0 * 3.14 );
[imageView setTransform:rotate];