Xcode iOS Project: What Is the Meaning of "Fopen Failed" and "Invalidating Cache..." at Start of Console Log When Running Debug Build

Coredata VFS flags - strange log

I'm pretty sure this is something you can ignore, that will probably be fixed when iOS 15.4 is out of beta.

According to the SQLite file-open flag documentation,

• Flag value 0x00000020 is SQLITE_OPEN_AUTOPROXY, for what that's worth
• This flag is one of several flags that "...have historically been ignored by sqlite3_open_v2()", however...
• "...future versions of SQLite might change so that an error is raised if any of the disallowed bits are passed into sqlite3_open_v2()"

What this seems to say is that the flag has no effect and hasn't had one for a while, so it doesn't matter if Core Data is using it internally. The message probably means that iOS 15.4 has a newer version of SQLite which has started to print warnings about it but hasn't started causing errors yet.

I'd expect this to be fixed when 15.4 is released, and in the meantime I encourage you to file a bug with Apple just in case.

What is the general structure when coding an iOS project if there is any?

There are a couple of ways you can approach developing an iOS project. But generally this is what you need to know.

• All your UI related designs can be implemented in Main.storyboard file in your project. Here you can create a View Controller and add various UI elements to them like button, labels etc.
• To make sure your views look the same across all device screen sizes, you need to use autolayouts which is the process of setting constraints to the UI elements so that they can be resized according to the screen size of the device they are being displayed on.
• For each View Controller created you have to assign a class file which is a .swift file. In this class file you have a function by default called viewDidLoad(). This method is executed when the view is displayed on the screen after running the code.
• For each UI element in a View Controller you can add IBOutlets and IBAction to their respective class file.

Here are a few links that can help you more:

• Tutorial for autolayouts: https://www.raywenderlich.com/443-auto-layout-tutorial-in-ios-11-getting-started
• Tutorial for Swift programming: https://www.raywenderlich.com/6338-swift-tutorial-part-1-expressions-variables-and-constants
• Get started with iOS: https://codewithchris.com/how-to-make-an-iphone-app/

Some other useful links:

• https://medium.com/ios-os-x-development/7-things-you-must-absolutely-do-before-writing-an-ios-app-a8bacf710c57
• https://www.raywenderlich.com/477-design-patterns-on-ios-using-swift-part-1-2

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