SWIFT ONLY -- Reading from NSInputStream

Question

Could you please explain me how do I read properly from an NSInputStream?

I couldn't understand what is UnsafePointer and what's the use of it (also for UnsafeArray).

The NSInputStream read function gets an CMutablePointer which can be filled with an UnsafePointer object.

It's a real mess comparing to Java's Streams.

What would you recommend ?

Thank you!

Solution

I have figured it out myself.

Look at this simple code:

let data: NSData = "Jonathan Yaniv.".dataUsingEncoding(NSUTF8StringEncoding, allowLossyConversion: true)
let stream: NSInputStream = NSInputStream(data: data)

var buffer = [UInt8](count: 8, repeatedValue: 0)

stream.open()

if stream.hasBytesAvailable {
    let result :Int = stream.read(&buffer, maxLength: buffer.count)
}

//  result = 8 -- because of the size of the buffer.
//  buffer contains the first 8 bytes repreenting the word "Jonathan"

Explanation: The read method signature: stream.read(<#buffer: UnsafeMutablePointer#>, maxLength: <#Int#>)

It gets a UnsafeMutablePointer as a first parameter, which means the method expects to get a POINTER to an array of type UInt8 - NOT the array itself

Therefore, we add the & notation before the name of the buffer variable. &buffer == the pointer to the UInt8 array object named buffer.

Comments

[Michael Welch]

Really hard to find in the documentation that using the & operator with an array returns an UnsafeMutablePointer<UInt8>. Without that knowledge it's really hard to figure out how to do what you did. So thanks!