ios - How can I programatically add a Gradient Layer over an image in Swift? -

i want place layer predefined transparent black gradient on top of uiimage content image loaded via web , creating effect of shadow on it.

i don't want via loading png such gradient.

i suggest creating custom subclass of uiview (or uiimageview, if want add gradient uiimageview). in init method of custom view, create cagradientlayer , add sublayer of view's layer. set black transparent gradient on layer.

you need override layoutsubviews() , change settings on gradient layer in case view's bounds change.

edit:

i created playground gist on github working example of this:

the code looks this:

import uikit import avfoundation   class imageviewwithgradient: uiimageview {   let mygradientlayer: cagradientlayer    override init(frame: cgrect)   {     mygradientlayer = cagradientlayer()     super.init(frame: frame)     self.setup()   }    required init(coder adecoder: nscoder)   {     mygradientlayer = cagradientlayer()     super.init(coder: adecoder)     self.setup()   }    func setup()   {     mygradientlayer.startpoint = cgpoint(x: 0, y: 0)     mygradientlayer.endpoint = cgpoint(x: 1, y: 1)     let colors: [cgcolorref] = [       uicolor.clearcolor().cgcolor,       uicolor(red: 0, green: 0, blue: 0, alpha: 0.3).cgcolor,       uicolor(red: 1, green: 1, blue: 1, alpha: 0.5).cgcolor,       uicolor(red: 0, green: 0, blue: 0, alpha: 0.3).cgcolor,       uicolor.clearcolor().cgcolor ]     mygradientlayer.colors = colors     mygradientlayer.opaque = false     mygradientlayer.locations = [0.0,  0.3, 0.5, 0.7, 1.0]     self.layer.addsublayer(mygradientlayer)   }    override func layoutsubviews()   {     mygradientlayer.frame = self.layer.bounds   } }   var aview = imageviewwithgradient(frame: cgrect(x: 0, y: 0, width: 500, height: 500))