制作一个tableview列表，动态加载数据和图像 包含单元格和一些文本。当它滚动得到抽搐和 激怒用户
是否有提高表格视图效果的想法？
class MainViewController: UIViewController,UITableViewDataSource, UITableViewDelegate {
@IBOutlet weak var listTable: UITableView!
override func viewDidLoad() {
super.viewDidLoad()
self.listTable.delegate = self
self.listTable.dataSource = self
self.listTable.separatorStyle = .None
self.listTable.registerNib(UINib(nibName: "cellOne", bundle: nil), forCellReuseIdentifier: "cellOne")
self.listTable.registerNib(UINib(nibName: "cellTwo", bundle: nil), forCellReuseIdentifier: "cellTwo")
self.listTable.registerNib(UINib(nibName: "cellThree", bundle: nil), forCellReuseIdentifier: "cellThree")
}
func numberOfSectionsInTableView(tableView: UITableView) -> Int{
return 1
}
func tableView(tableView: UITableView, heightForRowAtIndexPath indexPath: NSIndexPath) -> CGFloat {
if pageIndex == 7 {
return 120
} else if indexPath.row == 0 {
return 280
} else if (indexPath.row == 5 || indexPath.row == 4) {
return 200
} else if (indexPath.row == 8 || indexPath.row == 11) {
return 160
}
return 80
}
func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int{
return 50
}
func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
let cell = UITableViewCell()
let listArray = self.listDataArray[indexPath.row]
if indexPath.row == 0 && pageIndex != 7 {
var cell = tableView.dequeueReusabl eCellWithIdentifier("cellOne") as! cellOne!
if cell == nil {
tableView.registerClass(cellOne.classForCoder(), forCellReuseIdentifier: "cellOne")
cell = cellOne(style: UITableViewCellStyle.Default, reuseIdentifier: "cellOne")
}
cell.headLbl.text = "\(listArray["title"]!)".html2String
cell.addImageView.userInteractionEnabled = true
let guster = UITapGestureRecognizer(target: self, action: "addTarget:")
cell.addImageView.addGestureRecognizer(guster)
cell.addImageView.tag = 1
let qualityOfServiceClass = QOS_CLASS_BACKGROUND
let backgroundQueue = dispatch_get_global_queue(qualityOfServiceClass, 0)
dispatch_async(backgroundQueue, {
if listArray["image"] != nil && self.imagesLocalDictionary[indexPath.row] == nil {
let u = listArray["image"] as! String
let url = NSURL(string: u)
if url != nil {
let data = NSData(contentsOfURL: url!)
if data != nil {
dispatch_async(dispatch_get_main_queue(), { () -> Void in
cell.imageViews.image = UIImage(data: data!)
})
self.imagesLocalDictionary.setObject(data!, forKey: indexPath.row)
}
}
} else {
dispatch_async(dispatch_get_main_queue(), { () -> Void in
cell.imageViews.image = UIImage(data: self.imagesLocalDictionary[indexPath.row] as! NSData)
})
}
})
if Constants.sharedInstance.addData["1"] != nil {
cell.addImageView.image = UIImage(data: Constants.sharedInstance.addData["1"] as! NSData)
}
return cell
} else if indexPath.row == 4 && pageIndex != 7 {
var cell = tableView.dequeueReusableCellWithIdentifier("cellTwo") as! cellTwo!
if cell == nil {
tableView.registerClass(cellTwo.classForCoder(), forCellReuseIdentifier: "cellTwo")
cell = cellTwo(style: UITableViewCellStyle.Default, reuseIdentifier: "cellTwo")
}
cell.headLbl.text = "\(listArray["title"]!)".html2String
cell.addImageView.userInteractionEnabled = true
let guster = UITapGestureRecognizer(target: self, action: "addTarget:")
cell.addImageView.addGestureRecognizer(guster)
cell.addImageView.tag = 2
let qualityOfServiceClass = QOS_CLASS_BACKGROUND
let backgroundQueue = dispatch_get_global_queue(qualityOfServiceClass, 0)
dispatch_async(backgroundQueue, {
if listArray["image"] != nil && self.imagesLocalDictionary[indexPath.row] == nil {
let u = listArray["image"] as! String
let url = NSURL(string: u)
if url != nil {
let data = NSData(contentsOfURL: url!)
if data != nil {
dispatch_async(dispatch_get_main_queue(), { () -> Void in
cell.imageViews.image = UIImage(data: data!)
})
self.imagesLocalDictionary.setObject(data!, forKey: indexPath.row)
}
}
} else {
dispatch_async(dispatch_get_main_queue(), { () -> Void in
cell.imageViews.image = UIImage(data: self.imagesLocalDictionary[indexPath.row] as! NSData)
})
}
})
if Constants.sharedInstance.addData["2"] != nil {
cell.addImageView.image = UIImage(data: Constants.sharedInstance.addData["2"] as! NSData)
}
return cell
} else if indexPath.row == 5 && pageIndex != 7 {
var cell = tableView.dequeueReusableCellWithIdentifier("cellThree") as! cellThree!
if cell == nil {
tableView.registerClass(cellThree.classForCoder(), forCellReuseIdentifier: "cellThree")
cell = cellThree(style: UITableViewCellStyle.Default, reuseIdentifier: "cellThree")
}
cell.headLbl.text = "\(listArray["title"]!)".html2String
cell.addImageView.userInteractionEnabled = true
let guster = UITapGestureRecognizer(target: self, action: "addTarget:")
cell.addImageView.addGestureRecognizer(guster)
cell.addImageView.tag = 3
let qualityOfServiceClass = QOS_CLASS_BACKGROUND
let backgroundQueue = dispatch_get_global_queue(qualityOfServiceClass, 0)
dispatch_async(backgroundQueue, {
if listArray["image"] != nil && self.imagesLocalDictionary[indexPath.row] == nil {
let u = listArray["image"] as! String
let url = NSURL(string: u)
if url != nil {
let data = NSData(contentsOfURL: url!)
if data != nil {
dispatch_async(dispatch_get_main_queue(), { () -> Void in
cell.imageViews.image = UIImage(data: data!)
})
self.imagesLocalDictionary.setObject(data!, forKey: indexPath.row)
}
}
} else {
dispatch_async(dispatch_get_main_queue(), { () -> Void in
cell.imageViews.image = UIImage(data: self.imagesLocalDictionary[indexPath.row] as! NSData)
})
}
})
if Constants.sharedInstance.addData["3"] != nil {
cell.addImageView.image = UIImage(data: Constants.sharedInstance.addData["3"] as! NSData)
}
return cell
} else {
cell.backgroundColor = UIColor.groupTableViewBackgroundColor()
let container = UIView()
container.frame = CGRectMake(2, 1, tableView.frame.width-4, 78)
container.backgroundColor = UIColor.whiteColor()
cell.addSubview(container)
let headerLbl = UILabel()
headerLbl.backgroundColor = UIColor.clearColor()
headerLbl.frame = CGRectMake(120, 1, self.view.frame.width-130, 76)
headerLbl.numberOfLines = 0
headerLbl.font = UIFont(name: "TelegramHead", size: 18)
headerLbl.text = "\(listArray["title"]!)".html2String
headerLbl.lineBreakMode = NSLineBreakMode.ByCharWrapping
let imageView = UIImageView()
imageView.frame = CGRectMake(5, 5, 100, 68)
imageView.image = UIImage(named: "place_holder.jpg")
imageView.contentMode = UIViewContentMode.ScaleAspectFill
imageView.clipsToBounds = true
let blackLayerView = UIView();
blackLayerView.frame = CGRectMake(0, 0, 0, 0);
blackLayerView.backgroundColor = UIColor.blackColor();
blackLayerView.alpha = 0.4;
container.addSubview(imageView)
container.addSubview(blackLayerView);
container.addSubview(headerLbl)
if pageIndex == 7 {
container.frame = CGRectMake(2, 1, tableView.frame.width-4, 118)
imageView.frame = CGRectMake(5, 5, container.frame.width-10, 108)
blackLayerView.frame = imageView.frame;
headerLbl.frame = imageView.frame//CGRectMake(10, 5, self.view.frame.width-20, 100)
headerLbl.textColor = UIColor.whiteColor()
headerLbl.backgroundColor = UIColor.blackColor().colorWithAlphaComponent(0.2)
} else if (indexPath.row == 8 || indexPath.row == 11) && pageIndex != 7 {
let add = UIImageView()
add.frame = CGRectMake(2, 82, tableView.frame.width-4, 76)
//add.contentMode = UIViewContentMode.ScaleAspectFit;
cell.addSubview(add)
add.userInteractionEnabled = true
let guster = UITapGestureRecognizer(target: self, action: "addTarget:")
add.addGestureRecognizer(guster)
if Constants.sharedInstance.addData["4"] != nil && indexPath.row == 8{
add.image = UIImage(data: Constants.sharedInstance.addData["4"] as! NSData)
add.tag = 4
}
if Constants.sharedInstance.addData["5"] != nil && indexPath.row == 11{
add.image = UIImage(data: Constants.sharedInstance.addData["5"] as! NSData)
add.tag = 5
}
}
let qualityOfServiceClass = QOS_CLASS_BACKGROUND
let backgroundQueue = dispatch_get_global_queue(qualityOfServiceClass, 0)
dispatch_async(backgroundQueue, {
if listArray["image"] != nil && self.imagesLocalDictionary[indexPath.row] == nil {
let u = listArray["image"] as! String
let url = NSURL(string: u)
if url != nil {
let data = NSData(contentsOfURL: url!)
if data != nil {
dispatch_async(dispatch_get_main_queue(), { () -> Void in
imageView.image = UIImage(data: data!)
self.imagesLocalDictionary.setObject(data!, forKey: indexPath.row)
})
}
}
} else {
dispatch_async(dispatch_get_main_queue(), { () -> Void in
imageView.image = UIImage(data: self.imagesLocalDictionary[indexPath.row] as! NSData)
})
}
})
}
return cell
}
}
我确实获得了所需的功能。但是TableView上有一个非常不自然的混蛋导致糟糕的用户体验。
答案 0 :(得分：1)
您可以对此代码进行一些改进以提高性能。
我之前构建了一个复杂的表视图，并创建了为特定indexPath配置和返回重用单元的函数。
class LargeImageCell: UITableViewCell {
var imageView: UIImageView()
// in init, init the cell, add imageview as subview, setup constraints
func setContent(imageURL: URL) {
// load image from cache or fetch from network in background
}
}
// in tableview/view controller
func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
switch indexPath.row {
case 0:
return self.getLargeImageCell(indexPath: indexPath)
// all other cases
}
}
这仅仅是我实现我的方法，只是尝试减少单元格中的逻辑数量而且我总是发现最好创建自定义单元格而不是在cellForRowAt中添加它们，让单元格自行配置< / p>
func getLargeImageCell(indexPath: NSIndexPath) -> UITableViewCell {
let data = self.data[indexPath.row] // model from db
var cell: UITableViewCell
if let c = self.tableView.dequeueReusableCellWithIdentifier("largeImageCell") as? LargeImageCell {
cell = c
} else {
cell = LargeImageCell(style: UITableViewCellStyle.Default, reuseIdentifier: "largeImageCell")
}
cell.setContent(imageURL: data.imageURL)
return cell
}