0x00 Lesson

Swift ​​doesn't​​ like errors to happen when your program runs, which means it won’t let you run an error-throwing function by accident.

Instead, you need to call these functions using three new keywords: ​​do​​​ starts a section of code that might cause problems, ​​try​​​ is used before every function that might throw an error, and ​​catch​​ lets you handle errors gracefully.

If any errors are thrown inside the ​​do​​​ block, execution immediately jumps to the ​​catch​​​ block. Let’s try calling ​​checkPassword()​​ with a parameter that throws an error:

do {
  try checkPassword("password")
  print("That password is good!")
} catch {
  print("You can't use that password.")
}

When that code runs, ​​"You can't use that password"​​​ is printed, but “That password is good” won’t be - that code will never be reached. because the ​​error​​ is thrown.

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