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Before Swift 3 I was using:
guard let data = Data(contentsOf: url) else { print("There was an error!) return } However I now have to use do, try and catch. I'm not familiar with this syntax. How would I replicate this behaviour?
976
Swift is much stricter with respect to error handling and that is a good thing. The syntax, for example, is much more expressive. The try keyword is used to indicate that a method can throw an error. To catch and handle an error, the throwing method call needs to be wrapped in a do-catch statement.
try – You must use this keyword in front of the method that throws. Think of it like this: “You're trying to execute the method. catch – If the throwing method fails and raises an error, the execution will fall into this catch block. This is where you'll write code display a graceful error message to the user.
The difference here is that Data(contentsOf: url) does not return an Optional anymore, it throws.
So you can use it in Do-Catch but without guard:
do { let data = try Data(contentsOf: url) // do something with data // if the call fails, the catch block is executed } catch { print(error.localizedDescription) } Note that you could still use guard with try? instead of try but then the possible error message is ignored. In this case, you don't need a Do-Catch block:
guard let data = try? Data(contentsOf: url) else { print("There was an error!") // return or break } // do something with data If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
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