ios - Not using unwrapping in guard statements -

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i understand use of optionals enough know when necessary unwrap optional using exclamation point. why exclamation point isn't needed in guard statement?

this code works , compiles doesn't use exclamation points:

struct blog{    var author:string?   var name: string?  }  func bloginfo2(blog:blog?){   guard let blog = blog else {     print("blog nil")     return   }   guard let author = blog.author, name = blog.name else {     print("author or name nil")     return   }   print("blog:")   print(" author: \(author)")   print(" name: \(name)") }

this code works if put exclamation points:

struct blog{    var author:string?   var name: string?  }  func bloginfo2(blog:blog?){   guard let blog = blog! else {     print("blog nil")     return   }   guard let author = blog.author!, name = blog.name! else {     print("author or name nil")     return   }   print("blog:")   print(" author: \(author)")   print(" name: \(name)") }

isn't little contradictory or can explain why exclamation point isn't needed?

guard let unwrapped = optional optional binding (no link available directly correct book section, unfortunately). safely tries unwrap value in optional. if there value, unwrap succeeds, , value assigned given name.

you should heavily favor use of optional bindings, either guard or if (the difference scope of "unwrapped" name) on use of forced unwrapping !. failed force unwrap fatal error; program crash.


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