Do simulators match real device for pixel density for testing image assets?

I have a ContentView in my app which includes the line of code FileUploadProgressAttributes. this struct is defined in a file included in the target FileUploadProgressExtension. and it is an ActivityAttributes. in ContentView I imported FileUploadProgressExtension, and the xcode is able to find the FileUploadProgressAttributes during prebuild. but during build, it gives me Undefined symbols for architecture arm64: "FileUploadProgressExtension.FileUploadProgressAttributes.init(filename: Swift.String) -> FileUploadProgressExtension.FileUploadProgressAttributes the workaround i found is to add the file with the FileUploadProgressAttributes to my app's target, but I'm not sure if this is the right thing to do. When Xcode created the extension for me, it added the extension target as a target dependency of my app. so obviously if i added this file to my app target it makes the extension target pointless. First time working with widgets so I'm not sure if I'm missing something.

It seems like this is not supported in the Simulator because when I run my Unit tests and I try to read protection key-value the value is always nil, even if I set the data protection level when I write the file. On device this key returns the expected value. Is it possible to have the simulator support the data protection classes to run my unit tests? FYI Im testing on iOS

when I get results from picker: PHPickerViewController, didFinishPicking results: [PHPickerResult]) and I load the image using itemProvider .loadFileRepresentation (the itemProvider is the NSItemProvider provided by the PHPickerResult) will the url that's returned by this method be guaranteed to have the file extension ie, "file://image.jpeg" not "file://image" I want to know if i need to just check the extension to know its file type. (FYI in case this makes a difference, im only interested in user screenshots and screenrecordings)

if it set com.apple.CoreData.ConcurrencyDebug 1 as launch arg the app always crashes and i cant proceed into the app. is there a way to only raise a warning for these issues so that i can go into the app and check every place in one session for coredata errors?

When you update XCode it updates the sdk version, but do changes in the sdk take effect for apps running in a lower iOS version or only the corresponding iOS version or higher? For instance, https://developer.apple.com/documentation/ios-ipados-release-notes/ios-ipados-18_1-release-notes Do changes listed in the notes only happen for apps that are running on iOS 18.1 devices or on any device with the app compiled against the 18.1 sdk version? Am I the only person who finds the docs totally unclear on this?

Not sure if my question is weird or not, but I didnt find any documentation about an sdks access to an apps documents directory. Im assuming that because sdk is part of the sandbox that it can access and read from the documents directory? i.e. if i used NSFileManager.defaultManager.URLForDirectory( directory = NSCachesDirectory, inDomain = NSUserDomainMask, appropriateForURL = null, create = false, error = null, ) to write a file called "file.txt", then any sdk my app used has the ability to access the contents of said directory? If yes, why isnt this considered something more worth mentioning? usually in filemanager tutorials they never warn about this. FYI: Im asking more for iOS and iPadOs then MacOs.

Is it possible automatically grey out files that are too big when user select files using the UIDocumentPickerViewController?

https://developer.apple.com/documentation/ios-ipados-release-notes/ios-ipados-17_4-release-notes At the end of each release note there is a number, eg 121566625). What are these numbers?

Lets say i have an sdk that is not one of those listed, but it uses one of those listed. In this case, do i have to get the sdk im using to update their dependency to add the required signature and privacy manifest?

In https://developer.apple.com/support/third-party-SDK-requirements/ it says "Signatures are also required in these cases where the listed SDKs are used as binary dependencies. " As I am clueless regarding the technicalities of how sdks are added to a host app, the term binary dependency means nothing to me. For reference, our app uses Cocoapods to install all of the sdks.

I am assuming that even if the app i am using is not listed in the ios list of privacy impacting sdks, if they use a privacy impacting sdk in their sdk, then my app will be required to get the privacy manifest for that privacy impacting sdk: the rule must (logically!) be transitive. So far apple has not sent any email about the app needing to provide that for any of our sdks. but i am worried that maybe apple has not done the check for us yet, and by the time they do , we will be near deadline to submit an app.

For the PreviewProvider, is it possible to set the ios version which the preview will be made for or the preview will always use the latest ios version (e.g. ios 17)?

see the difference between the ios 15 screen shot and ios 17. the bottom one is the ios 17. if you look really closely you can see the whitespace is smaller. How can a developer make that new whitespace in code to follow the new style?

I am looking for a comparison chart between these three devices regarding what hardware each device support, showing every model of the devices.