如果您的 iPhone、iPad 或 iPod touch 速度变慢，执行 iOS 或 iPadOS 的全新安装可能有助于加快速度。全新的系统软件安装意味着您从零个第三方App Store应用程序、损坏的配置和损坏的设置开始，这可能会对性能产生积极影响。全新安装还可以解决您无法通过标准故障排除解决的问题。
您有几种方法可以全新安装 iOS 和 iPadOS。第一种方法是只使用 iPhone 或 iPad 擦除所有内容和设置，而第二种方法需要通过Mac或 PC 重新安装系统软件。
全新安装 iOS 或 iPadOS 会抹掉您的数据，但您始终可以选择预先创建文件和设置的备份。然后，您可以从头开始，或者恢复备份并从中断的地方继续。
删除所有内容和设置
iPhone 和 iPad 具有集成的“擦除(Erase)此 iPhone/iPad”工具，可让您快速将设备重置为出厂默认设置。它负责从创建数据备份到 iCloud(creating a backup of your data to iCloud)、停用“查找我的”和“激活锁(deactivating Find My and Activation Lock)”到擦除设备上的每一点个人数据等一切事务。
“擦除(Erase)此 iPhone/iPad”工具在技术上不会重新安装 iOS 或 iPadOS，但该过程确实会将系统软件恢复到与您从 iPhone 或 iPad 开箱即用的状态相似的状态。它也比通过Mac或 PC 执行恢复更快、更方便。
1.通过iPhone 或 iPad 上的主屏幕打开(Home Screen)设置(Settings)应用程序。
2. 选择通用(General)>传输或重置 iPhone(Transfer or Reset iPhone) >抹掉所有内容和设置(Erase All Content and Settings)（iOS 15/iPadOS 15 及更高版本）或通用(General)>重置(Reset)>抹掉所有内容和设置( Erase All Content and Settings)（iOS13/iOS 14/iPadOS 14 及更早版本）。
3. 选择继续(Continue)。
4. 输入您的 iOS 或 iPadOS 设备的设备密码。
5. 选择Finish Upload Then Erase将您的数据副本上传到 iCloud。如果您的 iCloud 空间不足，请通过 Mac或PC创建离线备份(create an offline backup via a Mac)。如果您不想创建备份，请选择立即擦除(Erase Now)。
警告(Warning)：如果您不创建备份，您将永久丢失所有数据，除了主动同步到 iCloud 的任何数据，例如您的照片、笔记和联系人。
6. 输入您的 Apple ID 密码，然后点击关闭(Turn Off )以停用“查找我的”(Find My)和“激活锁”(Activation Lock)。如果您的 iPhone 或 iPad 上的“查找”(Find My)未激活，您将不会看到此屏幕。
7. 点击擦除 iPhone(Erase iPhone) / iPad以确认您要擦除 iPhone 或 iPad 上的所有媒体、数据和设置。然后，等到“擦除(Erase)此 iPhone/iPad”工具将设备重置为出厂默认设置。这可能需要 10-15 分钟。
重置过程后，通过设置助手(Setup Assistant)设置您的 iPhone 或 iPad。进入“应用程序和数据(Apps & Data)”屏幕后，选择从 iCloud 备份(Restore from iCloud Backup)恢复或从 Mac 或 PC(Restore from Mac or PC)恢复以从备份恢复。或者，选择不传输应用程序和数据(Don’t Transfer Apps & Data)以开始将您的 iPhone 或 iPad 用作新设备。
通过 Finder/iTunes 恢复设备
如果您可以使用Mac或 PC，则可以使用(Mac)Finder或 iTunes执行 iOS 或 iPadOS 的实际全新安装。按照以下步骤禁用“查找我的”(Find My)和“激活锁”(Activation Lock)，备份您的 iPhone 或 iPad，并使用IPSW (iPhone/iPad Software) file重新安装最新版本的 iOS/iPadOS 。如果您在使用上面的“擦除(Erase)此 iPhone/iPad”工具时遇到问题，此方法最适合。
注意(Note)：如果您使用的是Windows PC，请确保在开始之前从 Microsoft Store或Apple 网站(Apple website)下载 iTunes 。(download iTunes from the Microsoft Store)
1. 在您的 iPhone 或 iPad 上前往设置(Settings)> Apple ID >查找(Find My)>查找我的 iPhone(Find My iPhone) / iPad。
2. 关闭“查找我的 iPhone(Find My iPhone) / iPad ”旁边的开关并输入您的Apple ID密码以验证该操作。
3. 通过USB(USB)将您的 iPhone 或 iPad 连接到Mac或 PC 。然后，解锁您的 iOS 或 iPadOS 设备并轻点“信任(Trust)” 。
4. 启动一个新的Finder窗口（如果您使用带有 macOS Catalina或更高版本的(Catalina)Mac）或打开iTunes。然后，在Finder(Finder)侧边栏或 iTunes 窗口的左上角选择您的 iPhone 或 iPad 。
5. 向下滚动到备份(Backups)部分。然后，选择Back up all of the data on your iPhone/iPad to this Mac/PC。如果要备份 Apple Watch 健康数据和密码，请选中(back up Apple Watch health data)加密本地备份( Encrypt local backup)旁边的框。然后，选择立即备份(Back Up Now)。
6.等待(Wait)Finder/iTunes完成iOS/iPadOS 设备上的数据备份。
7. 向上滚动到软件(Software)部分并选择恢复 iPhone(Restore iPhone) / iPad。
8. 选择恢复和更新。(Restore and Update.)
9. 选择同意(Agree)接受软件更新许可条款。
10.等到(Wait)Finder或 iTunes 为您的 iPhone 或 iPad 下载最新的 IPSW 文件（包含所有新功能和错误修复）。根据您的 Wi-Fi 或以太网(Ethernet)连接速度，这可能需要一个小时。然后它将自动开始重新安装系统软件。同时，请勿断开 iOS 或 iPadOS 设备与 PC 或Mac的连接。
重新安装 iOS 或 iPadOS 后，选择从此备份(Restore from this backup )恢复并选择一个备份来恢复您的数据。或者，选择设置为新 iPhone(Set up as new iPhone) / iPad以开始将您的 iPhone 或 iPad 用作新设备。
尝试恢复模式或 DFU 模式
在大多数情况下，只需将 iOS 或 iPadOS 恢复为出厂默认设置就足以为您的 iPhone 或 iPad 注入新的活力或解决与软件相关的持续问题。如果这没有帮助，请使用Mac或 PC 重新安装系统软件。
如果您无法在本教程中使用这两种方法干净地安装 iOS 或 iPadOS，则必须改用恢复模式(use Recovery Mode)或DFU（设备固件更新）模式(DFU (Device Firmware Update) Mode)。这些是可以修复设备严重问题的特殊恢复环境。如果需要，您还可以执行以前的操作系统版本的全新安装并在不越狱的情况下降级您的 iPhone 或 iPad(downgrade your iPhone or iPad without a jailbreak)。
How to Clean Install Any Version of iOS or iPadOS on iPhone and iPad
If your іPhone, iPad, or iPod touch is slowing down, performing a clean install of iOS or iPadOS might hеlp speed it up. A fresh system software installation means you begin wіth zero third-party App Store apps, broken configurations, and corrupt ѕettings, which could positively impact performance. A clean install can also fix problems yоu can’t resolve with standard troubleshooting.
You’ve got a couple of ways to clean install iOS and iPadOS. The first method involves erasing all content and settings using nothing but your iPhone or iPad, while the second method requires reinstalling the system software via a Mac or PC.
Clean installing iOS or iPadOS will erase your data, but you can always choose to create a backup of your files and settings beforehand. It’s then up to you to start all over from scratch or restore a backup and pick up where you left off.
Erase All Content and Settings
The iPhone and iPad feature an integrated “Erase This iPhone/iPad” tool that lets you quickly reset the device to factory defaults. It takes care of everything from creating a backup of your data to iCloud, deactivating Find My and Activation Lock, to wiping every bit of personal data off your device.
The “Erase This iPhone/iPad” tool doesn’t technically reinstall iOS or iPadOS, but the procedure does restore the system software to a state similar to what you get from an iPhone or iPad right out of the box. It’s also considerably faster and more convenient than performing a restore via a Mac or PC.
1. Open the Settings app via the Home Screen on your iPhone or iPad.
2. Select General > Transfer or Reset iPhone > Erase All Content and Settings (iOS 15/iPadOS 15 and later) or General > Reset > Erase All Content and Settings (iOS13/iOS 14/iPadOS 14 and earlier).
3. Select Continue.
4. Enter the device passcode of your iOS or iPadOS device.
5. Select Finish Upload Then Erase to upload a copy of your data to iCloud. If you lack space in iCloud, create an offline backup via a Mac or PC. If you don’t want to create a backup, select Erase Now.
Warning: If you don’t create a backup, you’ll permanently lose all data except for any that sync actively to iCloud—such as your photos, notes, and contacts.
6. Enter your Apple ID’s password and tap Turn Off to deactivate Find My and Activation Lock. You won’t see this screen if Find My is not active on your iPhone or iPad.
7. Tap Erase iPhone/iPad to confirm you want to erase all media, data, and settings on your iPhone or iPad. Then, wait until the “Erase This iPhone/iPad” tool resets the device to factory defaults. That can take anywhere between 10-15 minutes.
Work your way through the Setup Assistant to set up your iPhone or iPad after the reset procedure. Once you get to the Apps & Data screen, select Restore from iCloud Backup or Restore from Mac or PC to restore from a backup. Or, select Don’t Transfer Apps & Data to begin using your iPhone or iPad as a new device.
Restore Device via Finder/iTunes
If you have access to a Mac or PC, you can perform an actual clean install of iOS or iPadOS using Finder or iTunes. Follow the steps below to disable Find My and Activation Lock, back up your iPhone or iPad, and reinstall the latest version of iOS/iPadOS using an IPSW (iPhone/iPad Software) file. This method is best suited if you have trouble using the “Erase This iPhone/iPad” tool above.
Note: If you use a Windows PC, make sure to download iTunes from the Microsoft Store or the Apple website before you begin.
1. Go to Settings > Apple ID > Find My > Find My iPhone/iPad on your iPhone or iPad.
2. Turn off the switch next to Find My iPhone/iPad and enter your Apple ID password to authenticate the action.
3. Connect your iPhone or iPad to a Mac or PC via USB. Then, unlock your iOS or iPadOS device and tap Trust.
4. Launch a new Finder window (if you use a Mac with macOS Catalina or later) or open iTunes. Then, select your iPhone or iPad on the Finder sidebar or the top-left of the iTunes window.
5. Scroll down to the Backups section. Then, select Back up all of the data on your iPhone/iPad to this Mac/PC. If you want to back up Apple Watch health data and passwords, check the box next to Encrypt local backup. Then, select Back Up Now.
6. Wait until Finder/iTunes finishes backing up the data on your iOS/iPadOS device.
7. Scroll up to the Software section and select Restore iPhone/iPad.
8. Select Restore and Update.
9. Select Agree to accept the software update license terms.
10. Wait until Finder or iTunes downloads the latest IPSW file (containing all new features and bug fixes) for your iPhone or iPad. Depending on your Wi-Fi or Ethernet connection speed, that could take up to an hour. It will then automatically begin reinstalling the system software. Do not disconnect your iOS or iPadOS device from your PC or Mac in the meantime.
After reinstalling iOS or iPadOS, select Restore from this backup and pick a backup to restore your data. Or, choose Set up as new iPhone/iPad to begin using your iPhone or iPad as a new device.
Try Recovery Mode or DFU Mode
In most cases, simply restoring iOS or iPadOS to factory defaults should be more than enough to breathe new life into your iPhone or iPad or resolve persistent software-related issues. If that doesn’t help, use a Mac or PC to reinstall the system software.
If you can’t cleanly install iOS or iPadOS using both methods in this tutorial, you must use Recovery Mode or DFU (Device Firmware Update) Mode instead. These are special recovery environments that can fix severe problems with your device. You can also perform a clean install of a previous operating system version and downgrade your iPhone or iPad without a jailbreak if that’s what you want.
