UIImageView doesn't always tint template image

Easy fix solution:

Just add a new runtime attribute which will set the tintColor of the UIImageView to the specified color and ensure the image is tinted.

You will still need to set your image to be rendered as a template image in your Images.xcassets file.

This way you dont need any additional outlets, extensions or lines of code.

Also take note: It will not apply the tintColor in the user defined attribute if the tintColor on the view is the same color, they must be different.

Best solution I found that doesn't require a subclass or another IBInspectable attribute:

import UIKit

extension UIImageView {
    override open func awakeFromNib() {
        super.awakeFromNib()
        tintColorDidChange()
    }
}

The problem stems from the value for tint having no null state (within the Storyboard/Interface Builder UI). In order for Xcode to decide whether a tint should be applied to a UIImageView there appears to be an additional test. In Xcode this is apparently done by evaluating the constraints applied to UIImageView. As far as I know this test is undocumented.

If you only have a "Spacing to nearest neighbor" constraint on two (or one) sides of your UIImageView then the tint is not applied regardless of the value set for UIImage.renderingMode.

If you have a "Spacing to nearest neighbor" constraint on three (or all) sides of your UIImageView then the tint is applied if the UIImage.renderingMode is set to .alwaysTemplate.

In a purely Storyboard/Interface Builder approach you set the UIImage.renderingMode of an image by adding it to an Asset Catalogue and then changing the "Render As" property of the Image Set to "Template Image".