swift - Error: 'String' is not convertible to 'String!' -

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mapview.rac_valuesforkeypath("usertrackingmode", observer: self).subscribenextas {  // block handling

i error 'string' not convertible 'string!'. suggestions may mean?

i used think, string! same string, unwrapped string?...

  • xcode 7.3.1
  • swift 2.2
  • reactivecocoa 4.1.0

i think compiler reporting wrong error.

you can simplify expression using 

let key: string! = "usertrackingmode"

and use key instead of literal.

that simplify expression , compiler print real error.

type inferring complicated , when compiler doesn't find valid type combination, can show wrong error.


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