Since Xcode 8 and iOS10, views are not sized properly on viewDidLayoutSubviews

Question

It seems that with Xcode 8, on viewDidLoad, all viewcontroller subviews have the same size of 1000x1000. Strange thing, but okay, viewDidLoad has n

Answer 1

I already reported this issue to apple, this issue exist since a long time, when you are initializing UIViewController from Xib, but i found quite nice workaround. In addition to that i found that issue in some cases when layoutIfNeeded on UICollectionView and UITableView when datasource is not set in initial moment, and needed also swizzle it.

extension UIViewController {
    open override class func initialize() {
        if self !== UIViewController.self {
            return
        }
        DispatchQueue.once(token: "io.inspace.uiviewcontroller.swizzle") {
            ins_applyFixToViewFrameWhenLoadingFromNib()
        }
    }

    @objc func ins_setView(view: UIView!) {
        // View is loaded from xib file
        if nibBundle != nil && storyboard == nil && !view.frame.equalTo(UIScreen.main.bounds) {
            view.frame = UIScreen.main.bounds
            view.layoutIfNeeded()
        }
        ins_setView(view: view)
    }

    private class func ins_applyFixToViewFrameWhenLoadingFromNib() {
        UIViewController.swizzle(originalSelector: #selector(setter: UIViewController.view),
                                 with: #selector(UIViewController.ins_setView(view:)))
        UICollectionView.swizzle(originalSelector: #selector(UICollectionView.layoutSubviews),
                                 with: #selector(UICollectionView.ins_layoutSubviews))
        UITableView.swizzle(originalSelector: #selector(UITableView.layoutSubviews),
                                 with: #selector(UITableView.ins_layoutSubviews))
     }
}

extension UITableView {
    @objc fileprivate func ins_layoutSubviews() {
        if dataSource == nil {
            super.layoutSubviews()
        } else {
            ins_layoutSubviews()
        }
    }
}

extension UICollectionView {
    @objc fileprivate func ins_layoutSubviews() {
        if dataSource == nil {
            super.layoutSubviews()
        } else {
            ins_layoutSubviews()
        }
    }
}

Dispatch once extension:

extension DispatchQueue {

    private static var _onceTracker = [String]()

    /**
     Executes a block of code, associated with a unique token, only once.  The code is thread safe and will
     only execute the code once even in the presence of multithreaded calls.

     - parameter token: A unique reverse DNS style name such as com.vectorform. or a GUID
     - parameter block: Block to execute once
     */
    public class func once(token: String, block: (Void) -> Void) {
        objc_sync_enter(self); defer { objc_sync_exit(self) }

        if _onceTracker.contains(token) {
            return
        }

        _onceTracker.append(token)
        block()
    }
}

Swizzle extension:

extension NSObject {
    @discardableResult
    class func swizzle(originalSelector: Selector, with selector: Selector) -> Bool {

        var originalMethod: Method?
        var swizzledMethod: Method?

        originalMethod = class_getInstanceMethod(self, originalSelector)
        swizzledMethod = class_getInstanceMethod(self, selector)

        if originalMethod != nil && swizzledMethod != nil {
            method_exchangeImplementations(originalMethod!, swizzledMethod!)
            return true
        }
        return false
    }
}