Swift不好理解的地方
2016-08-31 本文已影响19人
此晨
1.String(类名) 。即 "类名"，例如
private struct Storyboard {
static let CellIdentifier = String(AnimationCollectionViewCell)
static let NibName =
String(AnimationCollectionViewCell)
static let a = String(ViewController)
}
2.images.count?? 不存在为0
return imageCollection?.images.count ?? 0
3.闭包的妙用 在 使用UICollectionView的VC里实现
backButtonTapped
class AnimationCollectionViewCell: UICollectionViewCell {
@IBOutlet weak var backButton: UIButton!
@IBOutlet weak var animationImageView: UIImageView!
@IBOutlet weak var animationTextView: UITextView!
var backButtonTapped: (() -> Void)?//闭包
func prepareCell(viewModel: AnimationCellModel) {
animationImageView.image = UIImage(named: viewModel.imagePath)
animationTextView.scrollEnabled = false
backButton.hidden = true
addTapEventHandler()
}
func handleCellSelected() {
animationTextView.scrollEnabled = false
backButton.hidden = false
self.superview?.bringSubviewToFront(self)
}
private func addTapEventHandler() {
backButton.addTarget(self, action: #selector(AnimationCollectionViewCell.backButtonDidTouch(_:)), forControlEvents: .TouchUpInside)
}
func backButtonDidTouch(sender: UIGestureRecognizer) {
backButtonTapped?()
}
}
3.map和闭包的连用
struct AnimationImageCollection {
private let imagePaths = ["1", "2", "3", "4", "5"]
var images: [AnimationCellModel]
init() {
//$0值imagePaths的元素
images = imagePaths.map { AnimationCellModel(imagePath: $0) }
}
}
struct AnimationCellModel {
let imagePath: String
init(imagePath: String?) {
self.imagePath = imagePath ?? ""
}
}
