Why try/catch block doesn't cover all the runtime exceptions?-CodePudding

What I try to do is

...
let path: URL? = URL(string: "")
    
    do {
        let data = try Data(contentsOf: path!)
    }
    catch {
        print("ERROR: \(error)")
    }
...

I know that this code won't work, but what I expect is to catch the error in the catch block instead I get a runtime exception and crash.

CodePudding user response：

try this

..
if let path = URL(string: "someStringForUrl") {
    
    do {
        let data = try Data(contentsOf: path)
    }
    catch {
        print("ERROR: \(error)")
    }
}
...

CodePudding user response：

You never reach the try, so you never reach the catch. Before any of that can happen, the path! forced unwrap fails and crashes the app.

(Crashing the app is a runtime exception, which is a completely different thing from the Swift try/catch mechanism. It doesn't not "cover all the runtime exceptions"; it doesn't cover any runtime exceptions. You're confusing apples with elephants; they are totally unrelated. Runtime exceptions are not thrown-caught Error objects, and vice versa.)