UIImage can not be nil in fact.
there are two ways to check whether image object has value Way 1: let uiimage as UIImage? and then set it initially to nil Way2: check its size property. if size is zero,it properly is empty object.
there are two ways to check whether image object has value Way 1: let uiimage as UIImage? and then set it initially to nil Way2: check its size property. if size is zero,it properly is empty object.
