在 Swift 中使用带有 iCarousel 的视觉格式语言

Question

我喜欢在我的快速项目中使用 iCarousel，但有一件事我无法克服；我想在我的项目中使用可视化语言来布局视图，但是每当我为 iCarousel 使用可视化格式时，它都不起作用。

我注意到问题出在TopMenuCarousel.translatesAutoresizingMaskIntoConstraints=false 属性上。

每当我禁用此属性时，我的 iCarousel 视觉格式约束都会被禁用，并且每当我启用它时，约束都可以正常工作，但我的 iCarousel 不会滚动并始终保持静止。

当前代码：

#

import UIKit
import iCarousel

class Step2_HomePage: UIViewController,iCarouselDelegate,iCarouselDataSource     {


let TopMenuCarouselCount = 5

    var TopMenuCarousel = iCarousel()

override func viewDidLoad() {
    super.viewDidLoad()

    print("Step2HomePage icinde")



    TopMenuCarousel = iCarousel(frame: CGRect())
    view.addSubview(TopMenuCarousel)
  //  TopMenuCarousel.clipsToBounds = true
    TopMenuCarousel.type = .Linear
    TopMenuCarousel.dataSource = self
    TopMenuCarousel.delegate = self






 let views = [ "TopMenuCarousel": TopMenuCarousel  ]

    // 2
    var allConstraints = [NSLayoutConstraint]()



    let TopMenuCarouselTop = NSLayoutConstraint.constraintsWithVisualFormat(
        "V:|-100-[TopMenuCarousel]",
        options: [],
        metrics: nil,
        views: views)
    allConstraints += TopMenuCarouselTop

    let TopMenuCarouselHorizontal = NSLayoutConstraint.constraintsWithVisualFormat(
        "H:|-0-[TopMenuCarousel]-0-|",
        options: [],
        metrics: nil,
        views: views)
    allConstraints += TopMenuCarouselHorizontal



    TopMenuCarousel.translatesAutoresizingMaskIntoConstraints=false
    NSLayoutConstraint.activateConstraints(allConstraints)




    // Do any additional setup after loading the view, typically from a nib.
}

func numberOfItemsInCarousel(carousel: iCarousel) -> Int {
    print("carousel number")
    return TopMenuCarouselCount

}

func carousel(carousel: iCarousel, viewForItemAtIndex index: Int, reusingView view: UIView?) -> UIView {
    print("carousel view icinde")
    let tempView = UIView(frame: CGRect(x: 0, y: 0 , width: 20, height: 20))

    tempView.backgroundColor = UIColor.blueColor()
    return tempView
}
override func didReceiveMemoryWarning() {
    super.didReceiveMemoryWarning()
    // Dispose of any resources that can be recreated.
}


}

#

Answer 1

看起来您没有为 iCarousel 对象设置任何高度。尝试将您的第一个约束更改为：

let TopMenuCarouselTop = NSLayoutConstraint.constraintsWithVisualFormat(
    "V:|-100-[TopMenuCarousel(20)]",
    options: [],
    metrics: nil,
    views: views)

这是原始代码的完整修改版本。我放大了视图（您的视图是 20x20），并添加了一些颜色以便更容易看到正在发生的事情。

import UIKit
import iCarousel

class Step2_HomePage: UIViewController,iCarouselDelegate,iCarouselDataSource {

    // array of colors to make it easy to see the individual Carousel views
    let arrayOfColors = [ UIColor.blueColor(), UIColor.redColor(), UIColor.yellowColor(), UIColor.orangeColor(), UIColor.greenColor()]

    let TopMenuCarouselCount = 5

    var TopMenuCarousel = iCarousel()

    override func viewDidLoad() {
        super.viewDidLoad()

        print("Step2HomePage icinde")

        self.view.backgroundColor = UIColor.lightGrayColor()

        // initialize the TopMenuCarousel object
        TopMenuCarousel = iCarousel(frame: CGRect())

        // add TopMenuCarousel to the view
        view.addSubview(TopMenuCarousel)

        // if clipsToBounds == true, TopMenuCarousel subviews will be clipped to the TopMenuCarousel frame
        // default is false

        //      TopMenuCarousel.clipsToBounds = true

        TopMenuCarousel.type = .Linear
        TopMenuCarousel.dataSource = self
        TopMenuCarousel.delegate = self

        TopMenuCarousel.backgroundColor = UIColor.purpleColor()

        let views = [ "TopMenuCarousel": TopMenuCarousel  ]

        var allConstraints = [NSLayoutConstraint]()

        // position TopMenuCarousel 100 from the Top, with a Height of 200
        let TopMenuCarouselTop = NSLayoutConstraint.constraintsWithVisualFormat(
            "V:|-100-[TopMenuCarousel(200)]",
            options: [],
            metrics: nil,
            views: views)

        allConstraints += TopMenuCarouselTop

        // set TopMenuCarousel to stretch the full Width of the view
        let TopMenuCarouselHorizontal = NSLayoutConstraint.constraintsWithVisualFormat(
            "H:|-0-[TopMenuCarousel]-0-|",
            options: [],
            metrics: nil,
            views: views)

        allConstraints += TopMenuCarouselHorizontal

        // this property *must* be set to false
        TopMenuCarousel.translatesAutoresizingMaskIntoConstraints=false

        NSLayoutConstraint.activateConstraints(allConstraints)

    }

    func numberOfItemsInCarousel(carousel: iCarousel) -> Int {
        print("carousel number \(TopMenuCarouselCount)")
        return TopMenuCarouselCount
    }

    func carousel(carousel: iCarousel, viewForItemAtIndex index: Int, reusingView view: UIView?) -> UIView {
        print("carousel view icinde", index)

        // create a 200 x 160 view to add to TopMenuCarousel
        let tempView = UIView(frame: CGRect(x: 0, y: 0 , width: 200, height: 160))

        // give it one of the colors
        tempView.backgroundColor =  arrayOfColors[index % arrayOfColors.count]

        return tempView
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }


}

Answer 2

约束已创建并激活但从未添加到视图中，您应该使用：

view.addConstraints(allConstraints)

之后

NSLayoutConstraint.activateConstraints(allConstraints)

正如 DonMag 所说，没有高度限制，这意味着如果 iCarousel 视图没有正确的固有尺寸，它将不会显示，您应该像 DonMag 写的示例一样添加显式高度。