做一个随机的方法，随机创建imageViews，其中一个图像的概率更大

So I Have an uIImageView 'image1' that is created every seconds with a timer.I have also another uIImageView 'image2'.What I would like is that appears on the screen randomly every seconds 'image1' or 'image2'instead of only 'image1' and also that 'image1' has more chances to appear on the screen like (80 % more) .How can I do this please ? sorry for my english I'm french :/So I Have an uIImageView 'image1' that is creat