Setting values in Swift for XYPieChart

Question

I need to set different values for my XYPieChart using Swift, but the entire XYPieChart.h file is written in Objective-C. I need to set values for number of slices, values for each slice, colors and text for each slice but I don't believe I know how to call them and set values for them correctly. I want my pie chart to display results for a poll. I've already created the IBOutlets for displaying the polls, but I'm not sure how to call these functions to set values for each of them:

@class XYPieChart;
@protocol XYPieChartDataSource <NSObject>
@required
- (NSUInteger)numberOfSlicesInPieChart:(XYPieChart *)pieChart;
- (CGFloat)pieChart:(XYPieChart *)pieChart valueForSliceAtIndex:(NSUInteger)index;
@optional
- (UIColor *)pieChart:(XYPieChart *)pieChart colorForSliceAtIndex:(NSUInteger)index;
- (NSString *)pieChart:(XYPieChart *)pieChart textForSliceAtIndex:(NSUInteger)index;
@end

So far, this is all I could figure out:

 @IBOutlet var chartDisplay1: [UIImageView]!
 func pieChart(pieChart:XYPieChart!,index:Int!) ->CGFloat
    {
        let value:NSNumber = self.values[index] as NSNumber
        return value.doubleValue
    }

The values I'm trying to set for each slice in this particular graph are my variables called votes and votes2. For this poll, those are the only two slices the pie chart needs. How do I set the different variables for numberOfSlicesInPieChart and valueForSliceAtIndex, and the rest?

score 2 · Answer 1 · edited May 23 '17 at 10:28

First you have to make sure you have a bridging header so you can access the objective C code, see this website:

How to call Objective-C code from Swift

Then, in the view controller you wish to generate the pie chart, you have to make sure you include the necessary methods to conform to the XYPieChartDataSource (at the bare minimum, the XYPieChartDelegate has additional optional methods), which are shown in swift here:

func pieChart(pieChart: XYPieChart!, valueForSliceAtIndex index: UInt) -> CGFloat {

    return CGFloat(self.slices[Int(index)] as NSNumber)

}

func numberOfSlicesInPieChart(pieChart: XYPieChart!) -> UInt {

    return UInt(self.slices.count)
}


func pieChart(pieChart: XYPieChart!, colorForSliceAtIndex index: UInt) -> UIColor! {
    return self.sliceColors[Int(index)] as UIColor
}

And modify the ViewController header accordingly:

class YourViewController: UIViewController, XYPieChartDelegate, XYPieChartDataSource {

A good idea to add these instance variables above your viewDidLoad too:

// Pie Chart Properties
    var slices:NSMutableArray = NSMutableArray(capacity: 10)
    var sliceColors:NSArray!
    var myPieChart:XYPieChart!
    var indexOfSlices:UInt!
    var numSlices:UInt = 0
    var valueAtSlice:Int = 0

After that, you have set the values you want for your pie chart, I have this in an initializePieChart() method:

let rect = CGRect(origin: CGPoint(x: 0, y: 0), size: UIScreen.mainScreen().applicationFrame.size)
let midPointx = UIScreen.mainScreen().applicationFrame.width/2
var midPointy:CGFloat = 0
var rad:CGFloat = 0
let point = CGPoint(x: midPointx, y: midPointy)

You then , and can initialize the pieChart as so:

    let aPieChart:XYPieChart = XYPieChart(frame: rect, center: point, radius: rad)
    self.myPieChart = aPieChart

Then finally, set the dataSource you modify the properties of the piechart as so:

   myPieChart.dataSource = self
    myPieChart.delegate = self

 //Various settings
        myPieChart.setPieBackgroundColor(UIColor(red: 0.251, green: 0.251, blue: 0.251, alpha: 1.0))
        myPieChart.startPieAngle = CGFloat(M_PI_2)
        myPieChart.animationSpeed = 2.0

    // Various settings
    myPieChart.showPercentage = true
    myPieChart.pieCenter = CGPointMake(midPointx, midPointy)
    myPieChart.userInteractionEnabled = false
    myPieChart.labelShadowColor = UIColor.blackColor()

    //For getting data into the slices
    self.sliceColors = [UIColor(red: 104/255, green: 1, blue: 67/255, alpha: 1),
        UIColor(red: 23/255, green: 247/255, blue: 252/255, alpha: 1),
        UIColor(red: 1, green: 0.231, blue: 0.188, alpha: 1)]

    for i in 0...2 {
        //This is just initializing the slices, you'll have to insert the data elsewhere using self.slices.replaceObjectAtIndex(0, withObject: dataVariable)

        var one:NSNumber = 0
        self.slices.addObject(one)
    }

Then finally, DONT FORGET TO RELOAD THE DATA and add to the subview

self.pieChartView.setTranslatesAutoresizingMaskIntoConstraints(false)
        myPieChart.reloadData()
        self.pieChartView.addSubview(myPieChart)

That should do it!

Setting values in Swift for XYPieChart

1 Answers1