UITextView with corner radius: White background of the input itself overlaps the round corners

I am trying to create a text field in objective-c with a big corner radius, like the searchField in iOS.
In my xib i have added a UITextField.
I style the textfield in objective-C like this:

// corner radius
 textField.layer.cornerRadius = 20.0f;
 textField.layer.masksToBounds = YES;
 textField.backgroundColor = [UIColor clearColor];
 
 [textField setFont:[UIFont fontWithName:@"Univers-Condensed-Medium" size:18.0]];
 

Result: The corners of the input are not visible, some white background overlays these.
You can see the problem in this image:

I have tried several things like:

textField.leftView.opaque = NO;
 textField.leftView.backgroundColor = [UIColor clearColor];
 
 textField.inputView.opaque = NO;
 textField.inputView.backgroundColor = [UIColor clearColor];
 
 textField.rightView.opaque = NO;
 textField.rightView.backgroundColor = [UIColor clearColor];
 

I even added an icon (just for testing) all gave the same result.
What do I need to do to make the corners visible?

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