与iOS 7的Swift 2.0兼容性

Question

I had my swift 1.2 code compatible with ios 7.1 to 8.4. Then when Apple released IOS 9, I migrated my code to swift 2 and my app supports now iOS 8 to 9, but will don't work with iOS 7.

For example, The try catch is not compatible with iOS 7 and Xcode mark it as an error.

var error: NSError? 
do {
   try NSFileManager.defaultManager().createDirectoryAtPath(dataPath, withIntermediateDirectories: false, attributes: nil)
} catch let error1 as NSError {
  error = error1
}

Also I have problems with UIAlertController because xcode gives me the following label @available(iOS 8.0, *)

how i could make compatible these two problems with iOS7?

Answer 1

For UIAlertController , you can use the code below, but for try catch no errors shows on my XCode.

           if #available(iOS 8.0, *) {
                let alertController = UIAlertController(title: "提示", message: hint+"不能为空", preferredStyle: .Alert)
                let OKAlert = UIAlertAction(title: "OK", style: UIAlertActionStyle.Default, handler: nil)
                alertController.addAction(OKAlert)
                self.presentViewController(alertController, animated: true, completion: nil)
            } else {
                let alertController: UIAlertView = UIAlertView(title: "提示", message: "不能为空", delegate: nil, cancelButtonTitle: "OK")
                alertController.show()
            }

EDIT:

Just wondering can you try:

if #available(iOS 8.0, *) {
do {
    let str = try NSString(contentsOfFile: "Foo.bar",
                           encoding: NSUTF8StringEncoding)
}
catch let error as NSError {
    print(error.localizedDescription)
}
}else{
#your code works on ios7
}