(ObjC -> Swift) Convert function "init" & "textureNamed"

Question

I get some errors when I try to convert 2 functions in Swift!

ObjC

@property (nonatomic, strong) NSMutableDictionary *textureCache;    

- (instancetype)init {
    if (self = [super init])
    {
        self.textureCache = [NSMutableDictionary dictionary];
    }
    return self;
}

- (SKTexture *)textureNamed:(NSString *)textureName {
    return _textureCache[textureName];
}

Swift

var textureCache: NSMutableDictionary?    

public func init() -> Self {
    return textureCache = NSMutableDictionary()
} 

public func textureNamed(textureName: String!) -> SKTexture! {
    return textureCache(textureName)
}

In the "init" function :

Expected identifier in function declaration -> (public func init -> Self)
Cannot assign a value of type 'NSMutableDictionary' to a value of type 'NSMutableDictionary?' -> (return textureCache = NSMutableDictionary())

And for the "textureNamed" function :

Cannot invoke 'textureCache' with an argument list of type '(String!)' -> (return textureCache(textureName))

If someone could help me, it would be awesome.

Eric Aya · Accepted Answer · 2015-04-13 11:07:51Z

0

I would try something like this:

class Test: NSObject {

  var textureCache = [String:SKTexture]()

  override init() {
    super.init()
  }

  func textureNamed(name: String) -> SKTexture? {
    return self.textureCache[name]
  }

}

answered Apr 13, 2015 at 11:07

Eric Aya

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Comments

bontoJR · Accepted Answer · 2015-04-13 11:08:04Z

Ok, let's decompose the problem.

Swift doesn't need a return type for init and if you have a superclass, you need to call super.init():

public func init() {
    super.init() //required if you have a superclass as the override after public
    textureCache = NSMutableDictionary()
}

Second problem, the method looks correct, the problem is related to the fact that textureCache is an Optional, so you have two solutions here.

Unwrap the variable and return the cached texture cached:

public func textureNamed(textureName: String!) -> SKTexture! {
    return textureCache?(textureName)
}

Or declare textureCache as non-optional value, because you are actually initializing it in the init method:

var textureCache: NSMutableDictionary  

public func textureNamed(textureName: String!) -> SKTexture! {
       return textureCache(textureName)
    }

Totof TonMomon · Accepted Answer · 2015-04-13 11:30:45Z

0

Thanks for your answers, it doesn't work in the both cases ! ^^ But you helped me a lot cuz I "found" a solution :

public init() {
    textureCache = NSMutableDictionary()
}

public func textureNamed(textureName: String!) -> SKTexture! {
    return textureCache?[textureName] as! SKTexture!
}

But I'm still not sure sure, the errors disappeared hoping it will not crash later...

answered Apr 13, 2015 at 11:30

Totof TonMomon

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