检查 NSSize 是否为零 - 比较“NSSize”类型的非可选值？

Question

I have a NSSize variable

var originalselectedimagesize:NSSize

if(originalselectedimagesize == nil)
{
}

I'm trying to check if NSSize is set? But i keep getting the following warning.How can i check if the value of NSSize is changed?

h(aka 'CGSize') to 'nil' always returns false

Answer 1

Because from the declaration, NSSize is not an optional. So checking a non-optional value for nil always return false.

In case if you have the following, then you won't get the warning.

var originalselectedimagesize:NSSize?

if(originalselectedimagesize == nil)
{
}

Answer 2

You can declare originalselectedimagesize as NSSize? ( Optional type of NSSize ), and set it to nil . Then, you can check if it has value like this:

var originalselectedimagesize: NSSize? = nil

// what ever...

// check for value
if let size = originalselectedimagesize {

}