MJRefresh跳动bug
iOS11之后，UITableView在刷新列表时contentOffset会发生变化，MJRefresh监听了contentOffset变化，会导致上拉加载更多组件闪动出现。我升级到最新版本v3.5.0，问题依旧存在，等官方修复。暂时解决办法：
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| tableView.estimatedRowHeight = 0
tableView.estimatedSectionHeaderHeight = 0
tableView.estimatedSectionFooterHeight = 0
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系统拍照裁剪不可拖动
我们在使用UIImagePickerController做照片选择器时，sourceType = .camera去拍照，设置allowsEditing = true拍完照的时候，可拖动照片裁剪为正方形，再使用裁剪后的照片。
官方bug，裁剪时无法拖动。这个bug从iOS6到现在的iOS14一直存在，不知道apple啥时候能解决。
问题讨论见：UIImagePicker allowsEditing stuck in center
解决方法：通过UIImagePickerController的拓展，重置UIScrollView的contentOffset
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extension UIImagePickerController {
func fixCannotMoveEditingBox() {
if let cropView = cropView,
let scrollView = scrollView,
scrollView.contentOffset.y == 0 {
let top = cropView.frame.minY
let bottom = scrollView.frame.height - cropView.frame.height - top
scrollView.contentInset = UIEdgeInsets(top: top, left: 0, bottom: bottom, right: 0)
var offset: CGFloat = 0
if scrollView.contentSize.height > scrollView.contentSize.width {
offset = 0.5 * (scrollView.contentSize.height - scrollView.contentSize.width)
}
scrollView.contentOffset = CGPoint(x: 0, y: -top + offset)
}
DispatchQueue.main.asyncAfter(deadline: .now() + 0.1) { [weak self] in
self?.fixCannotMoveEditingBox()
}
}
var cropView: UIView? {
return findCropView(from: self.view)
}
var scrollView: UIScrollView? {
return findScrollView(from: self.view)
}
func findCropView(from view: UIView) -> UIView? {
let width = UIScreen.main.bounds.width
let size = view.bounds.size
if width == size.height, width == size.height {
return view
}
for view in view.subviews {
if let cropView = findCropView(from: view) {
return cropView
}
}
return nil
}
func findScrollView(from view: UIView) -> UIScrollView? {
if let scrollView = view as? UIScrollView {
return scrollView
}
for view in view.subviews {
if let scrollView = findScrollView(from: view) {
return scrollView
}
}
return nil
}
}
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在创建UIImagePickerController时，调用拓展方法：
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| let imagePicker = UIImagePickerController()
imagePicker.sourceType = .camera
imagePicker.fixCannotMoveEditingBox()
imagePicker.allowsEditing = true
present(imagePicker, animated: true, completion: nil)
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