Xcode7,ios9 issue ,warning合集

1.Downcast from 'UIViewController' only unwraps optionals;did you mean to use'!'?

原：  let view = mainStory.instantiateInitialViewController() as! UIViewController

  window?.rootViewController = view

修改：

　　　if let view = mainStory.instantiateInitialViewController(){ 

            window?.rootViewController = view

        }

2.Call can throw, but it is not marked with 'try' and the error is not handled 或者 ambiguous reference to member 'appendpartwithfileurl'

原：formData.appendPartWithFileURL(filePath, name: "file")

修改：do {

       try formData.appendPartWithFileURL(filePath, name: "file")

} catch {

// TODO: handle error

}

3.Cannot convert value of type '[String : String?]' to expected argument type 'AnyObject?'

原：

let params = [ "url": urlTf.text ]

修改：let params = [ "url": urlTf.text  ?? "" ]

4.storyboard minimum font size greater than current font size

修改：在 inspector 下 修改 autoshrink fixed font size