Do-try-catch execution flow in Swift - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the purpose of the do block in Swift's do-try-catch execution flow?

The do block contains code that might throw an error. It allows you to try running this code and catch errors if they happen.

beginner

What keyword do you use to call a function that can throw an error inside a do block?

You use the try keyword before the function call to indicate it might throw an error.

intermediate

What happens when an error is thrown inside a do block?

The program immediately jumps to the matching catch block to handle the error. The rest of the do block is skipped.

intermediate

Can you have multiple catch blocks in Swift? What is their use?

Yes, you can have multiple catch blocks to handle different types of errors separately, making error handling more precise.

advanced

What is the role of the try? and try! keywords in Swift?

try? converts errors to optional values (nil if error), allowing safe error ignoring. try! forces the call and crashes if an error occurs, so use only when sure no error will happen.

What keyword do you use to handle errors thrown by a function in Swift?

A do

B catch

C throw

D try

You use try before calling a function that can throw an error.

What happens if an error is thrown inside a do block?

A Execution jumps to the matching <code>catch</code> block.

B The error is ignored.

C The program continues normally.

D The program crashes immediately.

When an error is thrown, Swift jumps to the catch block to handle it.

Which keyword is used to define the block that catches errors?

A try

B catch

C throw

D do

The catch block handles errors thrown in the do block.

What does try? do in Swift?

A Forces the function to throw an error.

B Ignores the error completely.

C Converts the error to an optional value.

D Catches the error automatically.

try? converts a thrown error into an optional nil value.

Can you have multiple catch blocks in Swift?

A Yes, to handle different error types.

B No, errors are handled in the do block.

C Yes, but only one will run.

D No, only one catch block is allowed.

Multiple catch blocks allow handling different errors separately.

Explain the flow of execution in a Swift do-try-catch block when an error is thrown.

Think about what happens step-by-step when an error occurs.

Describe the difference between try, try?, and try! in Swift error handling.

Focus on how each keyword treats errors differently.