XCode 编译错误：confirmationDialog 仅可用 IOS 15.0 或更高版本

Question

I'm an apprentice of Swift language and having an online course with tutorials.

While I was coding along with the instructor there was this "confirmationDialog is only available IOS 15.0 or newer." error presented. I had to write if #available(iOS 15.0, *) as compiler suggested. However the instructors compiler did not present the same error and she did not make any changes on her code.

My question is that why the above mentioned error occured on my compiler but not on the instructors? and how can I get rid of this error without adding if #available(iOS 15.0, *) ?

Thank you in advance.

Answer 1

The reason for the difference in your environment vs your instructors is that your instructor has their "deployment target" set to iOS 15 and yours is set to something lower like iOS 14 or 13. The deployment target setting governs the minimum version of iOS that your app is allowed to run on. Your instructor's app can only run on iOS 15 and later, so they don't need to use if #available(iOS 15.0, *) . This condition would always be true for them. In your case, since your app supports iOS 14, there are some scenarios where the confirmationDialog API will not be available to the user (since it was added in iOS 15), which is why you need the check. If you are okay with using a minimum version of iOS 15 like your instructor, you can change this setting in Xcode. Click your project name in the project navigator, click your app target, then click the "General" tab. You should see an area called "Deployment Info" and a dropdown for the iOS version. Change this to iOS 15.