如何修复SwiftUI中键盘抬起时视图动画突兀的问题

可以指定视图上移的动画曲线来匹配键盘动画，iOS系统的键盘动画参数（曲线、时长）可通过系统通知获取，用这些参数驱动SwiftUI动画就能让视图移动与键盘动画完全同步，解决突兀感。

核心思路 #

键盘弹出/收起时，系统会发送UIKeyboardWillShowNotification和UIKeyboardWillHideNotification通知，通知的userInfo字典包含键盘动画的时长和曲线参数。提取这些参数并转换成SwiftUI支持的Animation类型，再应用到视图位移上即可实现同步。

具体实现步骤 #

1. 监听键盘通知，获取动画参数
   在视图的onAppear中注册键盘通知监听，从通知的userInfo里提取关键参数：

• UIKeyboardAnimationDurationUserInfoKey：动画时长
• UIKeyboardAnimationCurveUserInfoKey：动画曲线（对应UIKit的UIView.AnimationCurve）
• UIKeyboardFrameEndUserInfoKey：键盘最终高度，用于计算视图上移距离

2. 将UIKit动画曲线转换为SwiftUI Animation
   编写扩展，把UIKit的动画曲线映射到SwiftUI的动画类型：

import SwiftUI

extension Animation {
    static func keyboardAnimation(duration: TimeInterval, curve: UIView.AnimationCurve) -> Animation {
        switch curve {
        case .easeInOut:
            return .easeInOut(duration: duration)
        case .easeIn:
            return .easeIn(duration: duration)
        case .easeOut:
            return .easeOut(duration: duration)
        case .linear:
            return .linear(duration: duration)
        @unknown default:
            return .easeInOut(duration: duration)
        }
    }
}

3. 应用同步动画到视图
   用@State保存键盘高度和对应动画参数，在视图位移时使用匹配的动画：

struct ContentView: View {
    @State private var keyboardHeight: CGFloat = 0
    @State private var keyboardAnimation: Animation = .default
    
    var body: some View {
        VStack {
            // 你的页面内容，比如输入框
            TextField("输入内容", text: .constant(""))
                .textFieldStyle(.roundedBorder)
                .padding()
            
            Spacer()
        }
        .padding(.bottom, keyboardHeight)
        .onAppear {
            // 监听键盘弹出通知
            NotificationCenter.default.addObserver(forName: UIResponder.keyboardWillShowNotification, object: nil, queue: .main) { notification in
                guard let userInfo = notification.userInfo,
                      let frame = userInfo[UIKeyboardFrameEndUserInfoKey] as? CGRect,
                      let duration = userInfo[UIKeyboardAnimationDurationUserInfoKey] as? TimeInterval,
                      let curveRawValue = userInfo[UIKeyboardAnimationCurveUserInfoKey] as? Int,
                      let curve = UIView.AnimationCurve(rawValue: curveRawValue) else {
                    return
                }
                
                keyboardHeight = frame.height
                keyboardAnimation = .keyboardAnimation(duration: duration, curve: curve)
            }
            
            // 监听键盘收起通知
            NotificationCenter.default.addObserver(forName: UIResponder.keyboardWillHideNotification, object: nil, queue: .main) { notification in
                guard let userInfo = notification.userInfo,
                      let duration = userInfo[UIKeyboardAnimationDurationUserInfoKey] as? TimeInterval,
                      let curveRawValue = userInfo[UIKeyboardAnimationCurveUserInfoKey] as? Int,
                      let curve = UIView.AnimationCurve(rawValue: curveRawValue) else {
                    return
                }
                
                keyboardHeight = 0
                keyboardAnimation = .keyboardAnimation(duration: duration, curve: curve)
            }
        }
        .animation(keyboardAnimation, value: keyboardHeight)
    }
}

注意事项 #

• 不要硬编码动画时长或曲线：不同iOS版本的键盘动画参数可能有细微调整，直接使用系统通知返回的参数能保证全版本适配。
• 该方案兼容iOS 13及以上的SwiftUI版本，覆盖目前主流iOS版本。

内容的提问来源于stack exchange，提问作者Danny