77 lines
3.4 KiB
Markdown
77 lines
3.4 KiB
Markdown
+++
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author = "FlintyLemming"
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title = "【归档】iOS 原生 UIKit 开发处理键盘遮挡输入框问题"
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slug = "1fd6cc7df7cf4583a7543b0018b32494"
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date = "2020-01-16"
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description = ""
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categories = ["Apple", "Coding"]
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tags = ["UIKit", "Swift"]
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image = "https://hf-public-source.mitsea.com:8840/images/blog/posts/2020/01/iOS%20%E5%8E%9F%E7%94%9F%20UIKit%20%E5%BC%80%E5%8F%91%E5%A4%84%E7%90%86%E9%94%AE%E7%9B%98%E9%81%AE%E6%8C%A1%E8%BE%93%E5%85%A5%E6%A1%86%E9%97%AE%E9%A2%98/slava-auchynnikau-B5nCJC-KpvA-unsplash.avif"
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# 概要
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目前项目中遇到小屏手机中弹出键盘时挡住输入框的问题，网上的方法我看都是要么修改当前 scrollview 的 offset，要么是修改 .view.frame 的y轴位置。但该方法在页面纵幅较短的情况下会出现问题，所以我这边使用修改约束的方法。
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# 预想方法
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通过修改最上方的元素到顶端的距离来实现需求
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### Risks
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动画做起来的话，没有移动 frame 来的简单，不能用 animated: true，得要自己写。当然我这边 base 里别人写好了。
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### Open Questions
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也许移动 frame 可行，但我这边就是会出现之前视频上出现的那个问题，没有找到解决方法。
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不过修改约束也没有经过长时间的充分测试，还没发现什么隐性问题。
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# 核心步骤
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1. 在 xib 中找到约束，并拖入 view 文件中
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2. 起个名字
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```swift
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@IBOutlet weak var topConstraint: NSLayoutConstraint!
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```
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3. 在 ViewController 里计算应当修改的数值，并进行偏移
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```swift
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@objc private func keyboardWillAppear(notification: NSNotification) {
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let keyboardRect = (notification.userInfo![UIResponder.keyboardFrameEndUserInfoKey] as! NSValue).cgRectValue
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let keyboardHeight = keyboardRect.size.height
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let screenHeight = self.view.frame.height
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let scrollViewOffset = cala001030View.scrollView.contentOffset.y
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let textFieldOffset = currentField.frame.origin.y - scrollViewOffset
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let visibleHeight = screenHeight - keyboardHeight - currentField.frame.size.height
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self.isNeedResetViewFrame = visibleHeight < textFieldOffset
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self.keyboardHeight = keyboardHeight
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let inputButtomToViewTop = currentField.frame.origin.y + currentField.frame.height + 30
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let keyboardTopToViewTop = screenHeight - keyboardHeight
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let shouldOffset = inputButtomToViewTop - keyboardTopToViewTop - scrollViewOffset
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if visibleHeight < textFieldOffset {
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self.cala001030View.topConstraint.constant = -shouldOffset
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}
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}
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```
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关于偏移量是如何计算出来的，会单独开一个文章来说明
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4. 键盘收回时，恢复原来的约束即可
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```swift
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@objc private func keyboardWillHide(notification: NSNotification) {
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self.cala001030View.topConstraint.constant = 0
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}
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```
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> Photo by [Slava Auchynnikau](https://unsplash.com/@auchynnikau?utm_content=creditCopyText&utm_medium=referral&utm_source=unsplash) on [Unsplash](https://unsplash.com/photos/the-sun-is-shining-through-the-clouds-over-the-mountains-B5nCJC-KpvA?utm_content=creditCopyText&utm_medium=referral&utm_source=unsplash)
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