iOS - masking with colorWithPatternImage without repeating on .png file

I'm triying to fill with pattern my mask images (.png)

UIImageView *imageView = (UIImageView*)_maskView.contentView;
imageView.image = [imageView.image imageWithRenderingMode:UIImageRenderingModeAlwaysTemplate];
imageView.tintColor = [UIColor colorWithPatternImage:image];

Now I have done what I want to do. But with a problem. Here is the screenshot:

In this screenshot I have these layers back to front;

1. mainImageView -> contains the waterfall image.


2. maskView -> lies on the top of the mainImageView. It is a custom UIView. It contains an imageView named contentView.


3. contentView -> An UIImageView. Subview of maskView. Contains the mask image. I use colorWithPatternImage code on its tintColor.

As you can see, my pattern image is tiling(or repeating or whatever you call).

I tried to resize the pattern image to the size of the imageView also tried resizing to high resolutions like 4000X4000 with no luck.

Tried something like

self.layer.contents = (id)[UIImage imageNamed:@"freshBackground.png"].CGImage;

but this code is filling the entire imageView.

Now I'm out of options. Can anyone help me on this? Thank you.