预先选择单元格中的项目

Question

所以我在加载时预先选择多个项目时遇到了一些麻烦。我的目标是让我的应用程序加载并有我的scroll bar目前完全预选的cell。

我目前在它下面有一个图标图标和文本，问题在于我的图标是预先选中并在开始时突出显示的，但紧接着的文本不是，除非我点击另一个单元格并单击原始细胞。所以我知道在swift 3.0代码将看起来像这样预先选择我的图标，但没有文本。我尝试了一些东西，但没有成功，所以我抹掉了试图预先选择代码中的文本的任何尝试。一直猜测了大约四个小时，所以我认为，而不是浪费一天的时间，我想我会问！

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) 

我为我粗糙的编码工作黑客道歉......我刚开始前几天，所以我真的只是通过试错下去。任何有关清理这些代码的见解都将不胜感激！

这是它目前是如何出现

This is the start up with only icon preselected

This is when I switch to the 2nd icon

不会让我后我的第三个图像，所以我想图像一个看起来像图像中的两个，除了最初的启动。

Answer 1

在你cellForItem方法添加 cell.isSelected = true

另外，如果我需要手动选择单元格我这样做是在cellForItem方法为好。因此，您不需要手动指定indexPath，因为您的方法本身具有相应的indexPath。

将您的collectionView.selectItem(at: selectIndexPath, animated: false, scrollPosition: UICollectionViewScrollPosition())移动到您想要在渲染时选择的单元格。

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 
    }