如何消除这些与使用 SwiftUI 相关的常见 Firebase 警告？答案

【问题标题】：How do I eliminate these common Firebase warnings related to using SwiftUI?如何消除这些与使用 SwiftUI 相关的常见 Firebase 警告？
【发布时间】：2021-06-05 02:37:55
【问题描述】：

我在我的 SwiftUI/Combine 应用程序中使用 Firebase，我注意到了几个我想解决的警告。他们没有破坏事情，但我想解决它们。我在使用具有最新 Swift 包依赖项的 Xcode 12.4 时收到这些警告：GoogleUtilities 7.2.2 和 Firebase 7.7.0。

这是控制台中出现的第一个警告：

[GoogleUtilities/AppDelegateSwizzler][I-SWZ001014] App Delegate does not conform to UIApplicationDelegate protocol.

作为参考，这是我配置 Firebase 的方式：

import SwiftUI
import Firebase

@main
struct MyApp: App {
    
    @StateObject var authState = AuthState()
    
    init() {
        FirebaseApp.configure()
    }
    
    var body: some Scene {
        
        WindowGroup {
            RootView()
                .environmentObject(authState)
        }
    }
}

这是第二个警告，在我使用 .navigationBarTitle 修饰符设置导航栏标题后出现。

[LayoutConstraints] Unable to simultaneously satisfy constraints.
Probably at least one of the constraints in the following list is one you don't want. 
    Try this: 
        (1) look at each constraint and try to figure out which you don't expect; 
        (2) find the code that added the unwanted constraint or constraints and fix it. 
(
    "<NSLayoutConstraint:0x280c8cfa0 'BIB_Trailing_CB_Leading' H:[_UIModernBarButton:0x109219b60]-(6)-[_UIModernBarButton:0x109218760'Fullres']   (active)>",
    "<NSLayoutConstraint:0x280c8cff0 'CB_Trailing_Trailing' _UIModernBarButton:0x109218760'Fullres'.trailing <= _UIButtonBarButton:0x109217100.trailing   (active)>",
    "<NSLayoutConstraint:0x280c8dd60 'UINav_static_button_horiz_position' _UIModernBarButton:0x109219b60.leading == UILayoutGuide:0x2816bcfc0'UIViewLayoutMarginsGuide'.leading   (active)>",
    "<NSLayoutConstraint:0x280c8ddb0 'UINavItemContentGuide-leading' H:[_UIButtonBarButton:0x109217100]-(0)-[UILayoutGuide:0x2816bcee0'UINavigationBarItemContentLayoutGuide']   (active)>",
    "<NSLayoutConstraint:0x280c88f00 'UINavItemContentGuide-trailing' UILayoutGuide:0x2816bcee0'UINavigationBarItemContentLayoutGuide'.trailing == _UINavigationBarContentView:0x109214320.trailing   (active)>",
    "<NSLayoutConstraint:0x280c8e530 'UIView-Encapsulated-Layout-Width' _UINavigationBarContentView:0x109214320.width == 0   (active)>",
    "<NSLayoutConstraint:0x280c892c0 'UIView-leftMargin-guide-constraint' H:|-(0)-[UILayoutGuide:0x2816bcfc0'UIViewLayoutMarginsGuide'](LTR)   (active, names: '|':_UINavigationBarContentView:0x109214320 )>"
)

Will attempt to recover by breaking constraint 
<NSLayoutConstraint:0x280c8cfa0 'BIB_Trailing_CB_Leading' H:[_UIModernBarButton:0x109219b60]-(6)-[_UIModernBarButton:0x109218760'Fullres']   (active)>

Make a symbolic breakpoint at UIViewAlertForUnsatisfiableConstraints to catch this in the debugger.
The methods in the UIConstraintBasedLayoutDebugging category on UIView listed in <UIKitCore/UIView.h> may also be helpful.

有没有人尝试解决这些警告？

【问题讨论】：

标签： ios firebase swiftui navigationbar

【解决方案1】：

第一条消息是由于 Firebase 尝试查找 AppDelegate，但由于您的应用遵循新的 SwiftUI 应用生命周期，因此它没有。

您可以通过添加AppDelegate 来消除此警告，如下所示：

import SwiftUI
import Firebase

class AppDelegate: NSObject, UIApplicationDelegate {
  func application(_ application: UIApplication,
                   didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey : Any]? = nil) -> Bool {
    FirebaseApp.configure()
    return true
  }
}

@main
struct MyApp: App {
  @UIApplicationDelegateAdaptor(AppDelegate.self) var delegate   
  @StateObject var authState = AuthState()
    
  init() {
    FirebaseApp.configure()
  }
    
  var body: some Scene {      
    WindowGroup {
      RootView()
        .environmentObject(authState)
    }
  }
}

更多详情请见my article on the topic。

附带说明，我们正在研究初始化 Firebase SDK 的其他方法（因为 swizzling 有其挑战） - 请参阅 this comment 上类似的 GitHub 问题。

至于第二个警告，这与 Firebase 无关。如果您搜索 StackOverflow，您会发现许多其他人也遇到了这个问题。 This question 看起来非常相似，并且有一个您可能想尝试的公认答案。

【讨论】：