My personal application created with xcode swiftUI disappears from my iphone, after 3 days message application not available. What is this development system for?

hello; The simulator exists but not in xcode 15.4? why? Why do we need to review the formatting for different versions of xcode, the same for development for MAC and IOS? This xcode bug too often. Still poorly documented.

Good morning why this NavigationStack { ContentView() } } .defaultSize(CGSize(width: 300, height: 800)) Gives an error with ios 15.5? Same for .fontWeight(.bold) If for each destination you have to change the weird source I stay with JAVA.