I’’ve been migrating a project to Swift 3 and a the piece of code below did not
require any modification but had wildly different results:
let myView = viewController.view
superview.addConstraints([
NSLayoutConstraint(
item: myView, attribute: .left,
relatedBy: .equal,
toItem: superview, attribute: .left,
multiplier: 1, constant: 0)
])
UIViewController’s view property is typed as UIView! so myView’s type is
inferred to UIView? in Swift 3 (previous inferred as UIView! in Swift 2). This
will crash in Swift 3 (not in Swift 2), because I think that myView’s optional
value is not bridged to the wrapped value in Objective-C when passed to
NSLayoutConstraint. Can somebody confirm that this proposal fixes this issue?
Regards,
David.
> On 03 Sep 2016, at 00:50, Douglas Gregor via swift-evolution
> <swift-evolution@swift.org> wrote:
>
> Hello Swift community,
>
> The review of SE-0140 "Bridge Optional As Its Payload Or NSNull" begins now
> and runs through September 8, 2016. The proposal is available here:
>
> https://github.com/apple/swift-evolution/blob/master/proposals/0140-bridge-optional-to-nsnull.md
>
> <https://github.com/apple/swift-evolution/blob/master/proposals/0140-bridge-optional-to-nsnull.md>
> Reviews are an important part of the Swift evolution process. All reviews
> should be sent to the swift-evolution mailing list at
>
> https://lists.swift.org/mailman/listinfo/swift-evolution
> <https://lists.swift.org/mailman/listinfo/swift-evolution>
> or, if you would like to keep your feedback private, directly to the review
> manager. When replying, please try to keep the proposal link at the top of
> the message:
>
> Proposal link:
>
> https://github.com/apple/swift-evolution/blob/master/proposals/0140-bridge-optional-to-nsnull.md
>
> <https://github.com/apple/swift-evolution/blob/master/proposals/0140-bridge-optional-to-nsnull.md>
> Reply text
>
> Other replies
> <https://github.com/apple/swift-evolution#what-goes-into-a-review-1>What
> goes into a review?
>
> The goal of the review process is to improve the proposal under review
> through constructive criticism and, eventually, determine the direction of
> Swift. When writing your review, here are some questions you might want to
> answer in your review:
>
> What is your evaluation of the proposal?
> Is the problem being addressed significant enough to warrant a change to
> Swift?
> Does this proposal fit well with the feel and direction of Swift?
> If you have used other languages or libraries with a similar feature, how do
> you feel that this proposal compares to those?
> How much effort did you put into your review? A glance, a quick reading, or
> an in-depth study?
> More information about the Swift evolution process is available at
>
> https://github.com/apple/swift-evolution/blob/master/process.md
> <https://github.com/apple/swift-evolution/blob/master/process.md>
> Thank you,
>
> -Doug
>
> Review Manager
>
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