一个UITableView头部添加一个UIView，都用snpkit(Swift代码)布局，一般代码写法
override func viewDidLoad() {
super.viewDidLoad()
self.view.addSubview(listView)
listView.snp.makeConstraints { make in
make.edges.equalToSuperview()
}
listView.tableHeaderView = headBackView
headBackView.snp.makeConstraints { make in
make.width.equalTo(listView.snp.width)
make.height.equalTo(100)
}
}
1
很明显，view遮住了cell，原因是：
- 在viewDidLoad中，
listView添加headerView时，headBackView的frame并没有生成，listView.tableHeaderView高度为0 - 后面刷新布局时，
headBackView高度改变已经不能影响listView.tableHeaderView的布局了 - 因此，需要线确定
headBackView的frame，再给listView.tableHeaderView赋值
override func viewDidLoad() {
super.viewDidLoad()
self.view.addSubview(headBackView)
headBackView.snp.makeConstraints { make in
make.top.left.right.equalToSuperview()
make.height.equalTo(100)
}
self.view.addSubview(listView)
listView.snp.makeConstraints { make in
make.edges.equalToSuperview()
}
}
// 在布局完成后的方法中，再操作
override func viewDidAppear(_ animated: Bool) {
super.viewDidAppear(animated)
if listView.tableHeaderView == nil {
headBackView.removeFromSuperview()
listView.tableHeaderView = headBackView
headBackView.snp.remakeConstraints { make in
make.width.equalTo(listView.snp.width)
make.height.equalTo(100)
}
}
}
2
在某个时间点，头部view高度变化
override func viewDidAppear(_ animated: Bool) {
super.viewDidAppear(animated)
if listView.tableHeaderView == nil {
headBackView.removeFromSuperview()
listView.tableHeaderView = headBackView
headBackView.snp.remakeConstraints { make in
make.width.equalTo(listView.snp.width)
make.height.equalTo(100)
}
DispatchQueue.main.asyncAfter(deadline: .now() + 3) {
self.headBackView.snp.updateConstraints { make in
make.height.equalTo(200)
}
}
}
}
3
view还是遮挡了
listView，但现在istView.tableHeaderView的高度有100，也就是说：listView.tableHeaderView被赋值后，snpkit不能在改变它的布局当
headView发生高度变化时，只能先取消istView.tableHeaderView赋值，添加到self.view中，更改布局，再赋值给istView.tableHeaderView
override func viewDidAppear(_ animated: Bool) {
super.viewDidAppear(animated)
if listView.tableHeaderView == nil {
headBackView.removeFromSuperview()
listView.tableHeaderView = headBackView
headBackView.snp.remakeConstraints { make in
make.width.equalTo(listView.snp.width)
make.height.equalTo(100)
}
DispatchQueue.main.asyncAfter(deadline: .now() + 3) {
self.listView.tableHeaderView = nil
self.view.addSubview(self.headBackView)
self.headBackView.snp.remakeConstraints { make in
make.width.equalTo(0)
make.height.equalTo(300)
}
// 添加一个延时，再去刷新
DispatchQueue.main.asyncAfter(deadline: .now() + 0.001) {
self.headBackView.removeFromSuperview()
self.listView.tableHeaderView = self.headBackView
self.headBackView.snp.remakeConstraints { make in
make.width.equalTo(self.listView.snp.width)
make.height.equalTo(300)
}
}
}
}
}
4
