How to unwrap optional value returns nil although it has value?

Question

I have this piece of code where i am unwrapping an optional value, and in the debugger there is a value in this optional variable. But for some reason it is giving me null pointer exception !!!

Can any one explain why its finding nil although there is a value !!

Answer 1

It looks like self.fullresolutionimages, the array/dictionary, is the nil that is causing the error.

make sure that you allocate that first, self.fullResolutionImages = [UIImage]() ;

Also, I am not 100% sure if doing the index when there are no contents will work, so you may want to append instead, self.fullResolutionImages.append(self.fullResolutionImage) , or insert this way, self.fullResolutionImages.insert(self.fullResolutionImage, atIndex: 0)

Answer 2

fullResolutionImages = nil，消息正确，不是吗？