Correct me if I'm wrong, but `weak` reference can not be `let` just by
definition: at some point in time such reference *can* become nil.
On 18.05.2016 16:22, Daniel Steinberg via swift-evolution wrote:
I would like to propose we modify the meaning of @IBOutlet in light of the
accepted proposal SE-0054 Abolish ImplicitlyUnwrappedOptional type. I think
this fits in with the current Swift 3 goals.
Currently we use “var” and “!” when we declare an outlet like this:
@IBOutlet weak var myLabel: UILabel!
The “!” in the declaration allows us to use the outlet like this without
unwrapping it
myLabel.text = “Hello"
We use “var” and “UILabel!" because myLabel starts its life out as nil and does
not have a value until the connection is made. i.e. myLabel must be an optional if
it accepts nil and the type is UILabel! instead of UILabel? so that we don’t have to
unwrap it each time we use it.
If we break the connection to the UILabel instance we crash at runtime for
attempting to unwrap nil.
Given this, I propose that we be able to write
@IBOutlet weak let myLabel: UILabel
In this case @IBOutlet has a meaning somewhat similar to lazy - it’s not that
myLabel doesn’t exist until we first call it, but @IBOutlet indicates that
myLabel should exist before we call it.
If the connection isn’t made and myLabel doesn’t exist, we should crash as we
do now. If the connection is not made in the nib or storyboard, this will crash
at development time.
This removes a case in which we use var - not because we want to change the
value of a property but because of a detail in the tooling.
This change also removes a case in which we use an Optional again for a detail
in lifecycle and tooling.
Best,
Daniel
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