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当点击不工作时更改uiCollectionViewCell内的视图

grand-central-dispatch uicollectionviewcell uicollectionview swift ios

NullHypothesis · 技术社区 · 6 年前

我在一个uiCollectionViewCell中有一个用户化身列表。当用户点击其中一项时,我想将所选项目添加到集合中,并将其突出显示以指示它已被点击。

不幸的是,用户界面似乎没有更新。有什么想法吗?

最初我加载图像并将其设置为圆形。如果我愿意的话,我甚至可以设置边框颜色,但现在我将其设置为清除。所有这些都在加载单元时工作:

 func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
        let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "cell", for: indexPath as IndexPath) as! UICollectionViewCell
        // Configure the cell
        let member: UserProfile = groupMembers[indexPath.item]
        let imgAvatar = cell.viewWithTag(2) as! UIImageView

        imgAvatar.layer.cornerRadius = contactAvatar.frame.size.width / 2
        imgAvatar.clipsToBounds = true
        imgAvatar.contentMode = UIViewContentMode.scaleAspectFill
        imgAvatar.layer.borderWidth = 2.0
        imgAvatar.layer.borderColor  = UIColor.clear.cgColor
        imgAvatar.layer.cornerRadius = 30.0

        let downloadURL = NSURL(string: member.avatarUrl)!
        imgAvatar.af_setImage(withURL: downloadURL as URL)

        return cell 
    }

下面是当您点击集合中任何给定的uiImageView时执行的代码,但它似乎没有更新图像:

 ///Fired when tapped on an image of a person
    func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {

         let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "cell", for: indexPath as IndexPath) as! UICollectionViewCell
        let tappedUser: UserProfile = groupMembers[indexPath.item]
        let imgAvatar = cell.viewWithTag(2) as! UIImageView

           ..add item to collection, etc.. 

           //Update imageview to indicate it's been tapped.
           DispatchQueue.main.async {
            contactAvatar.layer.cornerRadius = contactAvatar.frame.size.width / 2
            imgAvatar.clipsToBounds = true
            imgAvatar.contentMode = UIViewContentMode.scaleAspectFill
            imgAvatar.layer.borderWidth = 2.0
            imgAvatar.layer.cornerRadius = 30.0
            imgAvatar.layer.borderColor = UIcolor.blue.cgColor
            }

        }
    }

运行此代码时,它会命中断点以指示我已点击该项,但它不会更新UI。我确信有一个线程/UI问题,在这个问题中,集合视图不会“重新绘制”我对图像所做的更改。也许我不能改变一个收藏品内部视图的外观?

提前感谢您提供任何见解。

2 回复 | 直到 6 年前

agibson007 6 年前

您的didselect不正确。从集合视图中获取单元格。 cellForItem

 ///Fired when tapped on an image of a person
func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {

     let cell = collectionView.cellForItem(at:indexPath) as! UICollectionViewCell
    let tappedUser: UserProfile = groupMembers[indexPath.item]
    let imgAvatar = cell.viewWithTag(2) as! UIImageView

       ..add item to collection, etc.. 

       //Update imageview to indicate it's been tapped.
       DispatchQueue.main.async {
        contactAvatar.layer.cornerRadius = contactAvatar.frame.size.width / 2
        contactAvatar.clipsToBounds = true
        contactAvatar.contentMode = UIViewContentMode.scaleAspectFill
        contactAvatar.layer.borderWidth = 2.0
        contactAvatar.layer.cornerRadius = 30.0
        contactAvatar.layer.borderColor = UIcolor.blue.cgColor
        }

    }
}

使用手机,如果不起作用请告诉我。

Vinod Pandey 6 年前

您为获取单元实例而编写的代码不正确,请使用下面的代码行,其余的代码行都似乎正确,希望通过更改该行可以正常工作。

    let cell = collectionView.cellForItem(at:indexPath) as! UICollectionViewCell