CODEWITHSUNDEEP
iosxcodeswiftdebuggingsprite-kit
Razvan Julian
Razvan Julian

Reputation: 59

How to fix "Type of expression is ambiguous without more context" in Xcode

I have a Sprite Kit Game in Swift. After I updated Xcode and opened my project, I noticed some changes and an error to a pre-coded syntax saying: "Type of expression is ambiguous without more context" which wasn't there before. I marked the code with error below. Also Xcode says it's something wrong with .DataReadingMappedIfSafe. Do you know a way to fix it? Thank you in advance!

import UIKit
import SpriteKit

extension SKNode {
  class func unarchiveFromFile(file : String) -> SKNode? {
    if let path = NSBundle.mainBundle().pathForResource(file, ofType: "sks") {

      // Error occurs on the following line:
      var sceneData = NSData(contentsOfFile: path, options: .DataReadingMappedIfSafe, error: nil)!

      var archiver = NSKeyedUnarchiver(forReadingWithData: sceneData)
      archiver.setClass(self.classForKeyedUnarchiver(), forClassName: "SKScene")
      let scene = archiver.decodeObjectForKey(NSKeyedArchiveRootObjectKey) as! GameScene
      archiver.finishDecoding()
      return scene
    } else {
      return nil
    }
  }
}

Upvotes: 1

Views: 1800

Answers (2)

zaph
zaph

Reputation: 112857

You need to use try from Swift 2, see the Swift 2 iBook.The Swift 2.0 declaration is: convenience init(contentsOfFile path: String, encoding enc: UInt) throws, note the throws in place of the error parameter.

Error Handling

Error handling is the process of responding to and recovering from error conditions in your program. Swift provides first-class support for throwing, catching, propagating, and manipulating recoverable errors at runtime.”

You can learn more on Error Handling in Swift from the book: “Using Swift with Cocoa and Objective-C (Swift 2.1).” iBooks. https://itun.es/de/1u3-0.l

But in any case ignoring errors is not a best practice.

Upvotes: 1

Sahil Kapoor
Sahil Kapoor

Reputation: 11773

Try this:

class func unarchiveFromFile(file : String) -> SKNode? {
    if let path = NSBundle.mainBundle().pathForResource(file, ofType: "sks") {

        var sceneData: NSData?
        // Error occurs on the following line:
        do {
            sceneData = try  NSData(contentsOfFile: path, options: .DataReadingMappedIfSafe)
        } catch _ as NSError {

        }

        var archiver = NSKeyedUnarchiver(forReadingWithData: sceneData!)
        archiver.setClass(self.classForKeyedUnarchiver(), forClassName: "SKScene")
        let scene = archiver.decodeObjectForKey(NSKeyedArchiveRootObjectKey) as! GameScene
        archiver.finishDecoding()
        return scene
    } else {
        return nil
    }
}

Upvotes: 4

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