Memory leak _ContiguousArrayStorage?

Question

I'm new to swift.I'm running instrument tool for memory leaks.I found a leak "_ContiguousArrayStorage<String>"

Its leading to below part of the code

let myData = NSData(data: request.value!)
let buffer = Array(UnsafeBufferPointer(start: UnsafePointer<CUnsignedChar>(myData.bytes), count: myData.length))

Can anyone help me out?.

Anything wrong with above code?

Edit: Adding some more code.

let myData = NSData(data: request.value!)
var buffer = Array(UnsafeBufferPointer(start: UnsafePointer<CUnsignedChar>(myData.bytes), count: myData.length))

let responseArray: [CUnsignedChar] = Array(buffer)

let responseValue = BluetoothCommunicationManager.sharedInstance.parseData(responseArray,length: myData.length).0

let responseName = BluetoothCommunicationManager.sharedInstance.parseData(responseArray,length: myData.length).1

NSNotificationCenter.defaultCenter().postNotificationName(responseName, object: request, userInfo: responseValue as [NSObject : AnyObject])

The parseData method of the singleton class returns NSMutableDictionary.

func parseData(responseData: [CUnsignedChar]) -> NSMutableDictionary
{
        let infoDictionary = NSMutableDictionary()
        let subIndexValue = Int(responseData[5])
        infoDictionary.setValue(subIndexValue, forKey: KEY_SUB_INDEX)
        return responseData
}

Thanks in advance.

Answer 1

It looks like you are trying to convert the NSData to an array of CUnsignedChar . You don't need to use UnsafeBufferPointer or UnsafePointer to do that conversion. I suspect your use of the unsafe pointers is the root cause of your memory leak.

You can just create the array by passing it a Data object instead of an NSData object. Try this instead:

let myData = NSData(data: request.value!) as Data
let responseArray = [CUnsignedChar](myData)

let responseValue = BluetoothCommunicationManager.sharedInstance.parseData(responseArray, length: responseArray.count).0

let responseName = BluetoothCommunicationManager.sharedInstance.parseData(responseArray, length: responseArray.count).1

Answer 2

I had the same problem on a project that was NOT a mixture of Objective-C and Swift. It turned out that string interpolation can leak memory:

http://www.openradar.me/26761490

The TL;DR is to update your string interpolations to string concatenations instead.

So:

print("Cannot write to characteristic \(request.characteristic.UUID)")

Becomes:

print("Cannot write to characteristic " + request.characteristic.UUID)