How to pass arguments from one class into a UIView class? Swift - ios

Question

I have a UIView class in my app which plots a line graph. In there, I assign my graphPoints variables like so :
var graphPoints:[Int] = [1,2,3,5,7,9]
var graphPoints2:[Int] = [1,2,3,5,7,9]
What I want to do is pass an array of Int from another class and assign those variables, but I am not sure how to do it. Initially i put all my code into one func with array [Int] as parameters and called it from another class but it stopped plotting the graph altogether. How do i do this?
Here is my UIVIew GraphPlotter class code :
import UIKit
#IBDesignable class GraphPlotter: UIView {
var graphPoints:[Int] = [1,2,3,5,7,9]
var graphPoints2:[Int] = [1,2,3,5,7,9]
//1 - the properties for the gradient
var startColor: UIColor = UIColor.redColor()
var endColor: UIColor = UIColor.greenColor()
override func drawRect(rect: CGRect) {
let width = rect.width
let height = rect.height
//set up background clipping area
let path = UIBezierPath(roundedRect: rect,
byRoundingCorners: UIRectCorner.AllCorners,
cornerRadii: CGSize(width: 8.0, height: 8.0))
path.addClip()
//2 - get the current context
let context = UIGraphicsGetCurrentContext()
let colors = [startColor.CGColor, endColor.CGColor]
//3 - set up the color space
let colorSpace = CGColorSpaceCreateDeviceRGB()
//4 - set up the color stops
let colorLocations:[CGFloat] = [0.0, 1.0]
//5 - create the gradient
let gradient = CGGradientCreateWithColors(colorSpace,
colors,
colorLocations)
//6 - draw the gradient
var startPoint = CGPoint.zero
var endPoint = CGPoint(x:0, y:self.bounds.height)
CGContextDrawLinearGradient(context,
gradient,
startPoint,
endPoint,
[])
//calculate the x point
let margin:CGFloat = 40.0
let columnXPoint = { (column:Int) -> CGFloat in
//Calculate gap between points
let spacer = (width - margin*2 - 4) /
CGFloat((self.graphPoints.count - 1))
var x:CGFloat = CGFloat(column) * spacer
x += margin + 2
return x
}
// calculate the y point
let topBorder:CGFloat = 60
let bottomBorder:CGFloat = 50
let graphHeight = height - topBorder - bottomBorder
let maxValue = graphPoints2.maxElement()!
let columnYPoint = { (graphPoint2:Int) -> CGFloat in
var y:CGFloat = CGFloat(graphPoint2) /
CGFloat(maxValue) * graphHeight
y = graphHeight + topBorder - y // Flip the graph
return y
}
// draw the line graph
UIColor.flatTealColor().setFill()
UIColor.flatTealColor().setStroke()
//set up the points line
let graphPath = UIBezierPath()
//go to start of line
graphPath.moveToPoint(CGPoint(x:columnXPoint(0),
y:columnYPoint(graphPoints2[0])))
//add points for each item in the graphPoints array
//at the correct (x, y) for the point
for i in 1..<graphPoints.count {
let nextPoint = CGPoint(x:columnXPoint(i),
y:columnYPoint(graphPoints2[i]))
graphPath.addLineToPoint(nextPoint)
}
//Create the clipping path for the graph gradient
//1 - save the state of the context (commented out for now)
CGContextSaveGState(context)
//2 - make a copy of the path
let clippingPath = graphPath.copy() as! UIBezierPath
//3 - add lines to the copied path to complete the clip area
clippingPath.addLineToPoint(CGPoint(
x: columnXPoint(graphPoints.count - 1),
y:height))
clippingPath.addLineToPoint(CGPoint(
x:columnXPoint(0),
y:height))
clippingPath.closePath()
//4 - add the clipping path to the context
clippingPath.addClip()
let highestYPoint = columnYPoint(maxValue)
startPoint = CGPoint(x:margin, y: highestYPoint)
endPoint = CGPoint(x:margin, y:self.bounds.height)
CGContextDrawLinearGradient(context, gradient, startPoint, endPoint, [])
CGContextRestoreGState(context)
//draw the line on top of the clipped gradient
graphPath.lineWidth = 2.0
graphPath.stroke()
//Draw the circles on top of graph stroke
for i in 0..<graphPoints.count {
var point = CGPoint(x:columnXPoint(i), y:columnYPoint(graphPoints2[i]))
point.x -= 5.0/2
point.y -= 5.0/2
let circle = UIBezierPath(ovalInRect:
CGRect(origin: point,
size: CGSize(width: 5.0, height: 5.0)))
circle.fill()
let label = UILabel(frame: CGRectMake(0, 0, 200, 21))
label.center = CGPointMake(160, 284)
label.textAlignment = NSTextAlignment.Center
// label.text = "I'am a test label"
self.addSubview(label)
}
//Draw horizontal graph lines on the top of everything
let linePath = UIBezierPath()
//top line
linePath.moveToPoint(CGPoint(x:margin, y: topBorder))
linePath.addLineToPoint(CGPoint(x: width - margin,
y:topBorder))
//center line
linePath.moveToPoint(CGPoint(x:margin,
y: graphHeight/2 + topBorder))
linePath.addLineToPoint(CGPoint(x:width - margin,
y:graphHeight/2 + topBorder))
//bottom line
linePath.moveToPoint(CGPoint(x:margin,
y:height - bottomBorder))
linePath.addLineToPoint(CGPoint(x:width - margin,
y:height - bottomBorder))
let color = UIColor.flatTealColor()
color.setStroke()
linePath.lineWidth = 1.0
linePath.stroke()
}
}
DBController, func dosmth where I pass the array :
func dosmth(metadata: DBMetadata!) {
let documentsDirectoryPath = NSSearchPathForDirectoriesInDomains(.DocumentDirectory, .UserDomainMask, true)[0]
let localFilePath = (documentsDirectoryPath as NSString).stringByAppendingPathComponent(metadata.filename)
var newarray = [Int]()
do{
let data = try String(contentsOfFile: localFilePath as String,
encoding: NSASCIIStringEncoding)
print(data)
newarray = data.characters.split(){$0 == ","}.map{
Int(String.init($0).stringByTrimmingCharactersInSet(NSCharacterSet.whitespaceCharacterSet()))!}
print(newarray)
}
catch let error { print(error) }
//Probably wrong
GraphPlotter().graphPoints = newarray
GraphPlotter().graphPoints2 = newarray
}

Answer 1

So your drawRect method is based on the two variables graphPoints and graphPoints2. Create a method whose job is to update the arrays of these two variables, and then invoke setNeedsDisplay - which will go on to redraw the view.
func plotGraphPoints(gpArray1 : [Int], andMorePoints gpArray2: [Int] ) {
print("Old Values", self.graphPoints)
self.graphPoints = gpArray1
self.graphPoints2 = gpArray2
print("New values", self.graphPoints)
self.setNeedsDisplay()
}

Answer 2

First, I'd set these up so that any update will redraw the view:
var graphPoints:[Int]? { didSet { setNeedsDisplay() } }
var graphPoints2:[Int]? { didSet { setNeedsDisplay() } }
Note, I made those optionals, because you generally want it to handle the absence of data with nil values rather than dummy values. This does assume, though, that you'll tweak your implementation to detect and handle these nil values, e.g., before you start drawing the lines, do a
guard graphPoints != nil && graphPoints2 != nil else { return }
But, I notice that this whole class is IBDesignable, in which case, you probably want a prepareForInterfaceBuilder that provides sample data:
override func prepareForInterfaceBuilder() {
super.prepareForInterfaceBuilder()
graphPoints = [1,2,3,5,7,9]
graphPoints2 = [1,2,3,5,7,9]
}
Second, your other class needs to have a reference to this custom view.
If this "other" class is the view controller and you added the custom view via IB, you would just add a #IBOutlet for the custom view to this view controller. If you added this custom view programmatically, you'd just keep a reference to it in some property after adding it to the view hierarchy. But, however you added a reference to that view, say graphView, you'd just set these properties:
graphView.graphPoints = ...
graphView.graphPoints2 = ...
If this "other" class is something other than a view controller (and in discussion, it sounds like the class in question is a controller for processing of asynchronous DropBox API), you also need to give that class some mechanism to reference the view controller (and thus the custom view). You can accomplish this by either implementing a "completion handler pattern" or a "delegate-protocol" pattern.