滚动或拉动刷新后，UITableViewAutomaticDimension单元格会调整大小 [英] UITableViewAutomaticDimension Cells resize after scroll or pull to refresh
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问题描述
我添加了一个表格视图，并且在单元格中显示图像.我还添加了以下代码:
tableView.estimatedRowHeight = 175
tableView.rowHeight = UITableViewAutomaticDimension
以便使单元格根据图像调整大小.
但是当我启动我的应用程序时，我得到了这个信息:
直到我开始滚动时图像才加载...如果我向下滚动一半页面然后返回顶部，则显示此信息(正确):
如果我删除了like按钮，并且仅在一个单元格中放置了图片，那么当我启动我的应用程序时，如果我等了三秒钟却没有碰到任何东西，那么这些单元格就会自动调整大小.
有什么想法吗?我已经在Google上进行了研究，并尝试了针对旧版本Xcode的奇怪解决方案，但似乎没有任何效果！
这是我来自TableViewController的其余代码:
extension TimelineViewController: UITableViewDataSource {
func tableView(tableView: UITableView, heightForHeaderInSection section: Int) -> CGFloat {
return 46
}
func numberOfSectionsInTableView(tableView: UITableView) -> Int {
return timelineComponent.content.count
}
func tableView(tableView: UITableView, viewForHeaderInSection section: Int) -> UIView? {
let headerCell = tableView.dequeueReusableCellWithIdentifier("PostHeader") as! PostHeaderTableViewCell
let post = self.timelineComponent.content[section]
headerCell.post = post
return headerCell
}
func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return 1
}
func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCellWithIdentifier("PostCell") as! PostTableViewCell
//cell.postImageView?.image = UIImage(named: "Background.png")
let post = timelineComponent.content[indexPath.section]
post.downloadImage()
post.fetchLikes()
cell.post = post
cell.layoutIfNeeded()
return cell
}
}
extension TimelineViewController: UITableViewDelegate {
func tableView(tableView: UITableView, willDisplayCell cell: UITableViewCell, forRowAtIndexPath indexPath: NSIndexPath) {
timelineComponent.targetWillDisplayEntry(indexPath.section)
}
Download image code:
func downloadImage() {
// 1
image.value = Post.imageCache[self.imageFile!.name]
if image is not downloaded yet, get it
if (image.value == nil) {
imageFile?.getDataInBackgroundWithBlock { (data: NSData?, error: NSError?) -> Void in
if let data = data {
let image = UIImage(data: data, scale: 2.0)!
self.image.value = image
// 2
Post.imageCache[self.imageFile!.name] = image
}
}
}
}
// MARK: PFSubclassing
extension Post: PFSubclassing {
static func parseClassName() -> String {
return "Post"
}
override class func initialize() {
var onceToken : dispatch_once_t = 0;
dispatch_once(&onceToken) {
// inform Parse about this subclass
self.registerSubclass()
// 1
Post.imageCache = NSCacheSwift<String, UIImage>()
}
}
}
And here is my TableViewCell:
var post: Post? {
didSet {
postDisposable?.dispose()
likeDisposable?.dispose()
if let oldValue = oldValue where oldValue != post {
oldValue.image.value = nil
}
if let post = post {
postDisposable = post.image
.bindTo(postImageView.bnd_image)
likeDisposable = post.likes
.observe { (value: [PFUser]?) -> () in
if let value = value {
//self.likesLabel.text = self.stringFromUserList(value)
self.likeButton.selected = value.contains(PFUser.currentUser()!)
// self.likesIconImageView.hidden = (value.count == 0)
} else {
//self.likesLabel.text = ""
self.likeButton.selected = false
//self.likesIconImageView.hidden = true
}
}
}
}
}
我们非常感谢您的帮助！
解决方案
我猜想，当图像最终加载后，您需要重新加载单元格，因为使用new图像时tableView需要重新计算单元格的高度(以及整个contentHeight).大小到来
post.downloadImage { _ in
if tableView.indexPathForCell(cell) == indexPath {
tableView.reloadRowsAtIndexPaths([indexPath], animation: .None)
}
}
和downloadImage方法需要调用完成关闭.像这样的东西.
func downloadImage(completion: ((UIImage?) -> Void)?) {
if let imageValue = Post.imageCache[self.imageFile!.name] {
image.value = imageValue
completion?(imageValue)
return
}
//if image is not downloaded yet, get it
imageFile?.getDataInBackgroundWithBlock { (data: NSData?, error: NSError?) -> Void in
if let data = data {
let image = UIImage(data: data, scale: 2.0)!
self.image.value = image
// 2
Post.imageCache[self.imageFile!.name] = image
completion?(image)
} else {
completion?(nil)
}
}
}
I have added a table view, and I am display image in the cells. I have also added this code:
tableView.estimatedRowHeight = 175
tableView.rowHeight = UITableViewAutomaticDimension
So that the cells resize depending on the image.
When I launch my app though, I get this :
And the images do not load untill I start scrolling...If I scroll down half the page then go back to the top, I get this(which is correct):
Also if I remove the like button and just has the image alone in a cell, when I launch my app if I wait 3 seconds without touching anything the cells resize on they're own..?!
Any ideas? I have researched on google and tried the odd solution for the older versions of Xcode, But nothing seems to work!
Here is the rest of my code from the TableViewController:
extension TimelineViewController: UITableViewDataSource {
func tableView(tableView: UITableView, heightForHeaderInSection section: Int) -> CGFloat {
return 46
}
func numberOfSectionsInTableView(tableView: UITableView) -> Int {
return timelineComponent.content.count
}
func tableView(tableView: UITableView, viewForHeaderInSection section: Int) -> UIView? {
let headerCell = tableView.dequeueReusableCellWithIdentifier("PostHeader") as! PostHeaderTableViewCell
let post = self.timelineComponent.content[section]
headerCell.post = post
return headerCell
}
func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return 1
}
func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCellWithIdentifier("PostCell") as! PostTableViewCell
//cell.postImageView?.image = UIImage(named: "Background.png")
let post = timelineComponent.content[indexPath.section]
post.downloadImage()
post.fetchLikes()
cell.post = post
cell.layoutIfNeeded()
return cell
}
}
extension TimelineViewController: UITableViewDelegate {
func tableView(tableView: UITableView, willDisplayCell cell: UITableViewCell, forRowAtIndexPath indexPath: NSIndexPath) {
timelineComponent.targetWillDisplayEntry(indexPath.section)
}
Download image code:
func downloadImage() {
// 1
image.value = Post.imageCache[self.imageFile!.name]
if image is not downloaded yet, get it
if (image.value == nil) {
imageFile?.getDataInBackgroundWithBlock { (data: NSData?, error: NSError?) -> Void in
if let data = data {
let image = UIImage(data: data, scale: 2.0)!
self.image.value = image
// 2
Post.imageCache[self.imageFile!.name] = image
}
}
}
}
// MARK: PFSubclassing
extension Post: PFSubclassing {
static func parseClassName() -> String {
return "Post"
}
override class func initialize() {
var onceToken : dispatch_once_t = 0;
dispatch_once(&onceToken) {
// inform Parse about this subclass
self.registerSubclass()
// 1
Post.imageCache = NSCacheSwift<String, UIImage>()
}
}
}
And here is my TableViewCell:
var post: Post? {
didSet {
postDisposable?.dispose()
likeDisposable?.dispose()
if let oldValue = oldValue where oldValue != post {
oldValue.image.value = nil
}
if let post = post {
postDisposable = post.image
.bindTo(postImageView.bnd_image)
likeDisposable = post.likes
.observe { (value: [PFUser]?) -> () in
if let value = value {
//self.likesLabel.text = self.stringFromUserList(value)
self.likeButton.selected = value.contains(PFUser.currentUser()!)
// self.likesIconImageView.hidden = (value.count == 0)
} else {
//self.likesLabel.text = ""
self.likeButton.selected = false
//self.likesIconImageView.hidden = true
}
}
}
}
}
Any help is really appreciated!
解决方案
I guess, you need to reload the cell when the image is finally loaded, because tableView needs to recalculate cell height (and the whole contentHeight) when image with new size arrives
post.downloadImage { _ in
if tableView.indexPathForCell(cell) == indexPath {
tableView.reloadRowsAtIndexPaths([indexPath], animation: .None)
}
}
and downloadImage method needs to call completion closure. Something like that.
func downloadImage(completion: ((UIImage?) -> Void)?) {
if let imageValue = Post.imageCache[self.imageFile!.name] {
image.value = imageValue
completion?(imageValue)
return
}
//if image is not downloaded yet, get it
imageFile?.getDataInBackgroundWithBlock { (data: NSData?, error: NSError?) -> Void in
if let data = data {
let image = UIImage(data: data, scale: 2.0)!
self.image.value = image
// 2
Post.imageCache[self.imageFile!.name] = image
completion?(image)
} else {
completion?(nil)
}
}
}
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