UIcollectionview单元格问题Swift

Question

I have a simple collectionview controller like this:

class ViewController1: UICollectionViewController{

    override func viewDidLoad() {

        super.viewDidLoad()

        self.collectionView?.delegate = self
        self.collectionView?.dataSource = self

    }

    override func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {

        return 5
    }

override func  collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {

        let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "P", for: indexPath)

        return cell
    }
}

In the cell there is only an uiimageview and it has this constraints:

My problem is this:

when I execute this code on iPhone 6 simulator I get this (right way):

but when I execute this code on iPhone 5 simulator I get this (wrong way: the imageview starts before the screen on the left and the width and height are wrong respect to the constraints):

I am going crazy for this problem but I dont be able to solve. Can you help me?

Answer 1

You need to extend your ViewController1 to conform to UICollectionViewDelegateFlowLayout protocol. And implement methods to set size for each collection view cell like so:

class ViewController1: UICollectionViewController, UICollectionViewDelegateFlowLayout {
override func viewDidLoad() {

    super.viewDidLoad()

    self.collectionView?.delegate = self
    self.collectionView?.dataSource = self
}

override func viewDidAppear(_ animated: Bool) {
    super.viewDidAppear(animated)

    print(self.collectionView!.frame)
}

override func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {

    return 5
}

override func  collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {

    let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "P", for: indexPath)

    return cell
}

func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, minimumInteritemSpacingForSectionAt section: Int) -> CGFloat {
    return 0
}

func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, minimumLineSpacingForSectionAt section: Int) -> CGFloat {
    return 0
}

func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
    return CGSize(width: self.collectionView!.frame.size.width, height: 120.0)
}
}

It has hard coded values, but you should get the idea. Collection View width should be the max size for each item, so they won't get outside the box.