我希望 UITableView 的单元格能够适应其内容的大小在 iOS 10 和 11 中:
tableView.estimatedRowHeight = UITableViewAutomaticDimension // default in iOS 11
tableView.rowHeight = UITableViewAutomaticDimension
没有将 tableView.rowHeight 设置为显式数值，这是 iOS 11 中的新默认值。
UIView 没有内在的内容大小，因此我为其高度 anchor 设置了布局约束。但是，该 anchor 在运行时会中断。
UITableViewCell 中的哪些内部约束是单元格适应其内容所必需的？
这仅适用于 iOS 11:
class ViewController: UIViewController, UITableViewDataSource, UITableViewDelegate {
override func viewDidLoad() {
super.viewDidLoad()
let tableView = UITableView()
tableView.register(UITableViewCell.self, forCellReuseIdentifier: "cell")
tableView.estimatedRowHeight = UITableViewAutomaticDimension
tableView.rowHeight = UITableViewAutomaticDimension
tableView.delegate = self
tableView.dataSource = self
tableView.translatesAutoresizingMaskIntoConstraints = false
view.addSubview(tableView)
NSLayoutConstraint.activate([
tableView.topAnchor.constraint(equalTo: view.topAnchor),
tableView.bottomAnchor.constraint(equalTo: view.bottomAnchor),
tableView.leftAnchor.constraint(equalTo: view.leftAnchor),
tableView.rightAnchor.constraint(equalTo: view.rightAnchor)
])
}
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = UITableViewCell(style: UITableViewCellStyle.subtitle, reuseIdentifier: "cell")
let view = UIView()
view.backgroundColor = .blue
view.translatesAutoresizingMaskIntoConstraints = false
cell.contentView.addSubview(view)
NSLayoutConstraint.activate([
view.topAnchor.constraint(equalTo: cell.contentView.topAnchor),
view.bottomAnchor.constraint(equalTo: cell.contentView.bottomAnchor),
view.leftAnchor.constraint(equalTo: cell.contentView.leftAnchor),
view.rightAnchor.constraint(equalTo: cell.contentView.rightAnchor),
view.heightAnchor.constraint(equalToConstant: 300)
])
return cell
}
func numberOfSections(in tableView: UITableView) -> Int {
return 1
}
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return 1
}
}
在 iOS 10 中会引发此运行时错误，并且单元格大小不适应:
[LayoutConstraints] Unable to simultaneously satisfy constraints. Probably at least one of the constraints in the following list is one you don't want. Try this: (1) look at each constraint and try to figure out which you don't expect; (2) find the code that added the unwanted constraint or constraints and fix it. ( "NSLayoutConstraint:0x17009c020 V:|-(0)-[test.MyView:0x11dd1acb0] (active, names: '|':UITableViewCellContentView:0x11dd15220 )", "NSLayoutConstraint:0x17009c160 test.MyView:0x11dd1acb0.bottom == UITableViewCellContentView:0x11dd15220.bottom (active)", "NSLayoutConstraint:0x17009c390 test.MyView:0x11dd1acb0.height == 300 (active)", "NSLayoutConstraint:0x17009be40 'UIView-Encapsulated-Layout-Height' UITableViewCellContentView:0x11dd15220.height == 43.6667 (active)" )
Will attempt to recover by breaking constraint NSLayoutConstraint:0x17009c390 test.MyView:0x11dd1acb0.height == 300 (active)
Make a symbolic breakpoint at UIViewAlertForUnsatisfiableConstraints to catch this in the debugger. The methods in the UIConstraintBasedLayoutDebugging category on UIView listed in UIKit/UIView.h may also be helpful.
这适用于 iOS 10 和 11，但不使用新的 iOS 11 方法，因为 tableView.estimatedRowHeight 不是 UITableViewAutomaticDimension:
class ViewController_TableView: UIViewController, UITableViewDataSource, UITableViewDelegate {
override func viewDidLoad() {
super.viewDidLoad()
let tableView = UITableView()
tableView.register(UITableViewCell.self, forCellReuseIdentifier: "cell")
tableView.estimatedRowHeight = 30
tableView.rowHeight = UITableViewAutomaticDimension
tableView.delegate = self
tableView.dataSource = self
tableView.translatesAutoresizingMaskIntoConstraints = false
view.addSubview(tableView)
NSLayoutConstraint.activate([
tableView.topAnchor.constraint(equalTo: view.topAnchor),
tableView.bottomAnchor.constraint(equalTo: view.bottomAnchor),
tableView.leftAnchor.constraint(equalTo: view.leftAnchor),
tableView.rightAnchor.constraint(equalTo: view.rightAnchor)
])
}
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = UITableViewCell(style: UITableViewCellStyle.subtitle, reuseIdentifier: "cell")
let view = MyView()
view.backgroundColor = .blue
view.translatesAutoresizingMaskIntoConstraints = false
cell.contentView.addSubview(view)
NSLayoutConstraint.activate([
view.topAnchor.constraint(equalTo: cell.contentView.topAnchor),
view.bottomAnchor.constraint(equalTo: cell.contentView.bottomAnchor),
view.leftAnchor.constraint(equalTo: cell.contentView.leftAnchor),
view.rightAnchor.constraint(equalTo: cell.contentView.rightAnchor)
])
return cell
}
func numberOfSections(in tableView: UITableView) -> Int {
return 1
}
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return 1
}
}
class MyView: UIView {
override var intrinsicContentSize: CGSize {
get {
return CGSize(width: 300, height: 300)
}
}
}
您没有使委托(delegate)符合您的 Controller 。然后使用代码
class ViewController: UIViewController, UITableViewDelegate, UITableViewDataSource {
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view, typically from a nib.
let params : [String: Any] = ["q": "dd", "format": "json", "pretty": 1,"no_html": 1, "skip_disambig": 1]
Alamofire.request("https://api.duckduckgo.com", method: .get, parameters: params).responseJSON { (responseData) in
print(responseData)
}
let tableView = UITableView()
tableView.register(UITableViewCell.self, forCellReuseIdentifier: "cell")
tableView.estimatedRowHeight = 40
tableView.delegate = self
tableView.dataSource = self
tableView.translatesAutoresizingMaskIntoConstraints = false
view.addSubview(tableView)
NSLayoutConstraint.activate([
tableView.topAnchor.constraint(equalTo: view.topAnchor),
tableView.bottomAnchor.constraint(equalTo: view.bottomAnchor),
tableView.leftAnchor.constraint(equalTo: view.leftAnchor),
tableView.rightAnchor.constraint(equalTo: view.rightAnchor)
])
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = UITableViewCell(style: UITableViewCellStyle.subtitle, reuseIdentifier: "cell")
let view = UIView()
view.backgroundColor = .blue
view.translatesAutoresizingMaskIntoConstraints = false
cell.contentView.addSubview(view)
NSLayoutConstraint.activate([
view.topAnchor.constraint(equalTo: cell.contentView.topAnchor),
view.bottomAnchor.constraint(equalTo: cell.contentView.bottomAnchor),
view.leftAnchor.constraint(equalTo: cell.contentView.leftAnchor),
view.rightAnchor.constraint(equalTo: cell.contentView.rightAnchor),
view.heightAnchor.constraint(equalToConstant: 300) // this breaks on run time
])
return cell
}
func numberOfSections(in tableView: UITableView) -> Int {
return 1
}
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return 1
}
// use this delegate
func tableView(_ tableView: UITableView, heightForRowAt indexPath: IndexPath) -> CGFloat {
return UITableViewAutomaticDimension
}
}
关于iOS 11 : Adapt cell size to content with UITableViewAutomaticDimension，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/46542029/
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