預先選擇單元格中的項目

Question

所以我在加載時預先選擇多個項目時遇到了一些麻煩。我的目標是讓我的應用程序加載並有我的scroll bar目前完全預選的cell。

我目前在它下面有一個圖標圖標和文本，問題在於我的圖標是預先選中並在開始時突出顯示的，但緊接着的文本不是，除非我點擊另一個單元格並單擊原始細胞。所以我知道在swift 3.0代碼將看起來像這樣預先選擇我的圖標，但沒有文本。我嘗試了一些東西，但沒有成功，所以我抹掉了試圖預先選擇代碼中的文本的任何嘗試。一直猜測了大約四個小時，所以我認爲，而不是浪費一天的時間，我想我會問！

import UIKit 

    class IntroBar: UIView, UICollectionViewDataSource, UICollectionViewDelegate, UICollectionViewDelegateFlowLayout { 


    lazy var collectionView: UICollectionView = { 
    let layout = UICollectionViewFlowLayout() 
    let cv = UICollectionView(frame: .zero, collectionViewLayout: layout) 
    cv.backgroundColor = .black 
    cv.dataSource = self 
    cv.delegate = self 
    return cv 
}() 

let cellId = "cellId" 
let imageNames = ["Ex1","Ex2","Ex3","Ex4"] 
let titles = ["Ex1-1","Ex1-2","Ex1-3","Ex-1-4"] 

var loginController: LoginController? 


override init(frame: CGRect) { 
    super.init(frame: frame) 

    collectionView.register(MenuCell.self, forCellWithReuseIdentifier: cellId) 

    addSubview(collectionView) 
    addConstraintsWithFormat("H:|[v0]|", views: collectionView) 
    addConstraintsWithFormat("V:|[v0]|", views: collectionView) 


    let selectIndexPath = IndexPath(item: 0, section: 0) 
    collectionView.selectItem(at: selectIndexPath, animated: false, scrollPosition: UICollectionViewScrollPosition()) 



    setupHorizontalBar() 
} 

var horizontalBarLeftAnchorConstraint: NSLayoutConstraint? 

func setupHorizontalBar() { 
    let horizontalBarView = UIView() 
    horizontalBarView.backgroundColor = UIColor(white: 0.95, alpha: 1) 
    horizontalBarView.translatesAutoresizingMaskIntoConstraints = false 
    addSubview(horizontalBarView) 

    horizontalBarLeftAnchorConstraint = horizontalBarView.leftAnchor.constraint(equalTo: self.leftAnchor) 
    horizontalBarLeftAnchorConstraint?.isActive = true 

    horizontalBarView.topAnchor.constraint(equalTo: self.topAnchor).isActive = true 
    horizontalBarView.widthAnchor.constraint(equalTo: self.widthAnchor, multiplier: 1/4).isActive = true 
    horizontalBarView.heightAnchor.constraint(equalToConstant:4).isActive = true 
} 

func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) { 
    loginController?.scrollToMenuIndex(indexPath.item) 
} 

func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int { 
    return 4 
} 


func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell { 
    let cell = collectionView.dequeueReusableCell(withReuseIdentifier: cellId, for: indexPath) as! MenuCell 

    cell.imageView.image = UIImage(named: imageNames[indexPath.item])?.withRenderingMode(.alwaysTemplate) 

    cell.imageLabel.attributedText = NSMutableAttributedString(string: titles[indexPath.item], attributes: [NSFontAttributeName: UIFont.systemFont(ofSize: 10, weight: UIFontWeightHeavy), NSForegroundColorAttributeName: UIColor.black]) 
    cell.imageLabel.textAlignment = .center 
    cell.tintColor = .darkGray 

    return cell 
} 

func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize { 
    return CGSize(width: frame.width/4, height: frame.height) 
} 

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


required init?(coder aDecoder: NSCoder) { 
    fatalError("init(coder:) has not been implemented") 
} 

} 



class MenuCell: BaseCell { 

let imageLabel: UILabel = { 
    let label = UILabel() 
    return label 
}() 

    let imageView: UIImageView = { 
    let iv = UIImageView() 
    iv.image = UIImage(named: "Ex1")?.withRenderingMode(.alwaysTemplate) 
    iv.tintColor = .darkGray 
    return iv 
}() 

override var isHighlighted: Bool { 
    didSet { 
     imageView.tintColor = isHighlighted ? .white : .darkGray 
     imageLabel.textColor = isHighlighted ? .white : .black 
    } 
} 

override var isSelected: Bool { 
    didSet { 
     imageView.tintColor = isSelected ? .white : .darkGray 
     imageLabel.textColor = isSelected ? .white : .black 
    } 
} 


    override func setupViews() { 
     super.setupViews() 

     addSubview(imageLabel) 
     addSubview(imageView) 
     addConstraintsWithFormat("H:[v0(33)]", views: imageView) 
     addConstraintsWithFormat("V:[v0(33)]", views: imageView) 
     addConstraintsWithFormat("H:[v0(75)]", views: imageLabel) 
     addConstraintsWithFormat("V:[v0(50)]", views: imageLabel) 

我爲我粗糙的編碼工作黑客道歉......我剛開始前幾天，所以我真的只是通過試錯下去。任何有關清理這些代碼的見解都將不勝感激！

這是它目前是如何出現

This is the start up with only icon preselected

This is when I switch to the 2nd icon

不會讓我後我的第三個圖像，所以我想圖像一個看起來像圖像中的兩個，除了最初的啓動。

Answer 1

在你cellForItem方法添加 cell.isSelected = true

另外，如果我需要手動選擇單元格我這樣做是在cellForItem方法爲好。因此，您不需要手動指定indexPath，因爲您的方法本身具有相應的indexPath。

將您的collectionView.selectItem(at: selectIndexPath, animated: false, scrollPosition: UICollectionViewScrollPosition())移動到您想要在渲染時選擇的單元格。

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

    let cell = collectionView.dequeueReusableCell(withReuseIdentifier: cellId, 
               for: indexPath) as! MenuCell 

    cell.imageView.image = UIImage(named: imageNames[indexPath.item])?.withRenderingMode(.alwaysTemplate) 

    cell.imageLabel.attributedText = ... 
    cell.imageLabel.textAlignment = .center 
    cell.tintColor = .darkGray 

    if wantThisCellSelected == true { 
     cell.isSelected = true 
     collectionView.selectItem(at: indexPath, animated: false, 
            scrollPosition: UICollectionViewScrollPosition()) 
    } else { 
     cell.isSelected = false 
     collectionView.deselectItem(at: indexPath, animated: false) 
    } 
     return cell 
    }