How to create a UIProgressView with gradient progress in Swift

I am an iOS engineer, and last week I was converting a UI design into a screen on Xcode's interface builder, when I faced this layout:

Interface design with a progres view containing a gradient fill.

So, the designer wanted a progress view containing a gradient fill, and this is how I built it on code:

First of all, I've created a UIImage extension to initiate it with an array of UIColor, which will be turned into a gradient. Also, I created a GradientOrientation enum to specify if the gradient is vertical or horizontal. This way, we can use the UIImage init in other UI components, such as UIImageView.

Finally I've created the GradientProgressView, a class extended from UIProgressView which contains firstColor and secondColor. These variables were marked as IBInspectable, so they can be assigned at the Interface Builder. By changing these colors either on storyboard or on code, the progress view's progressImage will be set as a gradient starting at firstColor and ending at secondColor.

That being done, we just need to change the GradientProgressView's first and second colors and voilà, our progress views are now gradient-ready.

Gradient progress view examples