In an application I wrote, I have a process that parses a large amount of data from Core-Data and displays it on a graph. While doing this processing, I am also writing data to a CSV file. I created a separate class called CSVLine that helps with the creation of the CSV file.
For my 140k test case written my Objective-C code takes approximately 12 seconds to run. After "transferring" the class to the fast one, it now takes from 280 to 360 seconds. Obviously I did something terrible.

Using Tools, I was able to identify the "slow" method and I was wondering if I did anything in SWIFT to cause the problem.

ObjC

- (void)newLine {
//    NSLog(@"Appending %@", self.csvString);

    [outData appendData:[self csvData] ];
    [self clear];
}

- (void)clear {

    // Erase every single value

    for (NSUInteger i = 0; i < [values count]; i ++) {
        values[i] = @"";
    }
}

      

        
        
        
      

    

Swift

func newLine() {
    outData.appendData(csvData())
    clear()
}


// Clear out the Array
func clear() {
    for (var i = 0; i < values.count; i++) {
        values[i] = ""
    }
}

      

        
        
        
      

    

I am working with different types of data that are all written to one CSV file, so there are a lot of blank lines. For this, I designed this class to have an array keys

and an array values

. This keys

stores the column names for the CSV file, and the values ​​will store either a space or an index value key

for that data item.

Example:

Keys = [speed, heading, lat, lon]

can be [200,300, "," "]

or ["," "," 38.553 "," 25.2256 "]

Once I'm done with the line, I'll write a comma list of values ​​into the internal data structure and clear the string (remove all elements in the array values

). It seems that this slowdown is happening with the fast-paced class. Is there something blatantly "slow" I do when I zero out my array?

Complete Quick class

@objc class CSVLineSwift : NSObject {

    // Define Arrays
    var keys: [String] = [String]()
    var values: [String] = [String]()

    var outData : NSMutableData = NSMutableData()

    override init() {

    }

    // Singelton Operator - Thread Safe :: http://code.martinrue.com/posts/the-singleton-pattern-in-swift
    class var instance : CSVLineSwift {

        // Computed Property
        struct Static {
            static var instance : CSVLineSwift?
            static var token: dispatch_once_t = 0
            }

        dispatch_once(&Static.token) {
            Static.instance = CSVLineSwift();
        }

        return Static.instance!
    }

    // Erase existing Data
    func newFile() {
        outData = NSMutableData();
        outData.appendData(headerData())
    }

    func csvString() -> String {
        return ",".join(values)
    }

    func csvData() -> NSData {
        let string = csvString()
        let data = string.dataUsingEncoding(NSUTF8StringEncoding)
        return data!
    }


    func addField(field : String) {
        keys.append(field)
        values.append("")
    }

    func setValueForKey(value:String, key:String) {

        if let index = find(keys, key) {
            values[index] = value
        } else {
            print( "ERROR -- There was no key: \(key) in the header Array")
        }
    }

    func headerString() -> String {
        return ",".join(keys)
    }

    func headerData() -> NSData {
       return headerString().dataUsingEncoding(NSUTF8StringEncoding)!
    }


    func newLine() {
        outData.appendData(csvData())
        clear()
    }


    // Clear out the Array
    func clear() {
        for (var i = 0; i < values.count; i++) {
            values[i] = ""
        }
    }

    func writeToFile(fileName : String) {
        outData.writeToFile(fileName, atomically: true)
    }

}