背景:
替换iOS推送通知的默认左侧图标

实现原理：
1.客户端实现互动通知扩展，并实现相关代理函数
2.推送消息到苹果服务器的时候携带 "mutable-content": 1 的字段，然后端上的通知扩展程序就会被激活，然后代理函数回调用，下载图片资源，替换通知图片

官方例子

{
   "aps" : {
      "category" : "SECRET",
      "mutable-content" : 1,
      "alert" : {
         "title" : "Secret Message!",
         "body"  : "(Encrypted)"
     },
   },
   "ENCRYPTED_DATA" : "Salted__·öîQÊ$UDì_¶Ù∞èΩ^¬%gq∞NÿÒQùw"
}

测试例子

{"aps":{"alert":"This is some fancy message.","badge":6,"sound": "default","mutable-content": 1},"avatar_url":"https://img.isupermeet.com/MTcyMjIzNjMxMTczMSM4NzIjanBn.jpg"}

注意："mutable-content": 1 一定到对，否则代理函数无法调用（ps: 笔者做的时候参考了网上资料文档，有些资料文档里的 mutable-content 字段是错误的，如 mutable_content, 导致无法调试通）

注意：plist文件里的字段顺序有严格的要求， INStartCallIntent在前，INSendMessageIntent 在后

其他问题：
1.默认创建出来的通知扩展，代码文件是蓝色的

image.png

需要将其转换成group文件: 选中蓝色的文件夹，右键选择 Covert to Group 完成转换

image.png

2.编译运行报错：

ycle inside Runner; building could produce unreliable results.
Cycle details:
→ Target 'Runner' has copy command from '/Users/gg/Library/Developer/Xcode/DerivedData/Runner-bylfgjqadshquibfkfwdljlsxqkj/Build/Products/Release-iphoneos/spns.appex' to '/Users/gg/Library/Developer/Xcode/DerivedData/Runner-bylfgjqadshquibfkfwdljlsxqkj/Build/Products/Release-iphoneos/Runner.app/PlugIns/spns.appex'
○ That command depends on command in Target 'Runner': script phase “[CP] Copy Pods Resources”
○ That command depends on command in Target 'Runner': script phase “[CP] Embed Pods Frameworks”
○ That command depends on command in Target 'Runner': script phase “Thin Binary”
○ Target 'Runner' has process command with output '/Users/gg/Library/Developer/Xcode/DerivedData/Runner-bylfgjqadshquibfkfwdljlsxqkj/Build/Products/Release-iphoneos/Runner.app/Info.plist'
○ Target 'Runner' has copy command from '/Users/gg/Library/Developer/Xcode/DerivedData/Runner-bylfgjqadshquibfkfwdljlsxqkj/Build/Products/Release-iphoneos/spns.appex' to '/Users/gg/Library/Developer/Xcode/DerivedData/Runner-bylfgjqadshquibfkfwdljlsxqkj/Build/Products/Release-iphoneos/Runner.app/PlugIns/spns.appex'

解决参考：stackoverflow
检查发现我的 Thin Binary 不在最下面，然后移动了最下面解决问题，最终效果如下：

image.png

猜测：Xcode升级后，脚本运行顺序出了问题

更多实现细节参考资料：

Zego - 互动通知实现
互动通知实现