Reponse to http://pastie.org/9945352

no-unwraps.swift

func StringFromURL (url : NSURL, 
    error errorPointer : NSErrorPointer) -> (NSString?) {

    var error : NSError?
    
    // Request data
    let data: NSData
    if let some = NSData(contentsOfURL:url, options: NSDataReadingOptions(rawValue:0), error: &error) {
        data = some
    } else {
        errorPointer.memory = error
        return nil
    }
    
    // Convert the data to a UTF-8 string
    let string: String
    if let some = NSString(data: data, encoding: NSUTF8StringEncoding)
        string = some
    } else {
        errorPointer.memory = BuildError(1, "Unable to build string from data")
        return nil
    }

    // Return the string    
    return string
}

original.swift

// Return NSError from code and reason
func BuildError(code : Int, reason : String) -> NSError {
    let errorDomain = "com.sadun.examples"
    let error = NSError(domain: errorDomain, code: code,
        userInfo: [
            NSLocalizedDescriptionKey:reason,
            NSLocalizedFailureReasonErrorKey:reason])
    return error
}

// Fetch string using standard Swift if-let
func StringFromURL(url : NSURL, 
    error errorPointer : NSErrorPointer) -> (NSString?) {
    var error : NSError?
    
    // Request data
    if let data = NSData(contentsOfURL:url, options: 
        NSDataReadingOptions(rawValue:0), error: &error) {

        // Convert the data to a UTF-8 string
        if let string = NSString(data: data, encoding: NSUTF8StringEncoding) {
            // Return the string
            return string
        }
        errorPointer.memory = BuildError(1, "Unable to build string from data")
        return nil
    }
    errorPointer.memory = error
    return nil
}

VERSUS

// Fetch string using a linear flow 
func StringFromURL (url : NSURL, 
    error errorPointer : NSErrorPointer) -> (NSString?) {

    var error : NSError?
    
    // Request data
    let data = NSData(contentsOfURL:url, 
        options: NSDataReadingOptions(rawValue:0), error: &error)
    if (data == nil) {
        errorPointer.memory = error
        return nil
    }
    
    // Convert the data to a UTF-8 string
    let string = NSString(data: data!, encoding: NSUTF8StringEncoding)
    if (string == nil) {
        errorPointer.memory = 
            BuildError(1, "Unable to build string from data")
        return nil
    }

    // Return the string    
    return string
}