Rawan Rawan - 1 month ago 12
iOS Question

How to implement range slider in Swift

I'm trying to implement Range Slider and I used custom control called NMRangeSlider.

But when I use it, the slider doesn't appear at all. Could it be also because it's all written in Objective-C?

This is how I've currently implemented it:

var rangeSlider = NMRangeSlider(frame: CGRectMake(16, 6, 275, 34))
rangeSlider.lowerValue = 0.54
rangeSlider.upperValue = 0.94
self.view.addSubview(rangeSlider)

Answer

UPDATE:

It did not show to me, because it was all white. So the solution, without using any other framework and sticking with this one - you need to set all the views for all the components and then it will display well:

enter image description here


I have tried to import it in Swift as I used it before in Objective-C code, but without any luck. If I set everything properly and add it either in viewDidLoad() or viewDidAppear(), nothing gets displayed. One thing is worth mentioning, though - when I enter View Debug Hierarchy, the slider actually is there on the canvas:

enter image description here

But it's simply not rendered with all the colors that I did set before adding in it to the view. For the record - this is the code I used:

override func viewDidAppear(animated: Bool) {
    var rangeSlider = NMRangeSlider(frame: CGRectMake(50, 50, 275, 34))
    rangeSlider.lowerValue = 0.54
    rangeSlider.upperValue = 0.94

    let range = 10.0
    let oneStep = 1.0 / range
    let minRange: Float = 0.05
    rangeSlider.minimumRange = minRange

    let bgImage = UIView(frame: rangeSlider.frame)
    bgImage.backgroundColor = .greenColor()
    rangeSlider.trackImage = bgImage.pb_takeSnapshot()

    let trackView = UIView(frame: CGRectMake(0, 0, rangeSlider.frame.size.width, 29))
    trackView.backgroundColor = .whiteColor()
    trackView.opaque = false
    trackView.alpha = 0.3
    rangeSlider.trackImage = UIImage(named: "")

    let lowerThumb = UIView(frame: CGRectMake(0, 0, 8, 29))
    lowerThumb.backgroundColor = .whiteColor()
    let lowerThumbHigh = UIView(frame: CGRectMake(0, 0, 8, 29))
    lowerThumbHigh.backgroundColor = UIColor.blueColor()

    rangeSlider.lowerHandleImageNormal = lowerThumb.pb_takeSnapshot()
    rangeSlider.lowerHandleImageHighlighted = lowerThumbHigh.pb_takeSnapshot()
    rangeSlider.upperHandleImageNormal = lowerThumb.pb_takeSnapshot()
    rangeSlider.upperHandleImageHighlighted = lowerThumbHigh.pb_takeSnapshot()

    self.view.addSubview(rangeSlider)

    self.view.backgroundColor = .lightGrayColor()
}

Using the method for capturing the UIView as UIImage mentioned in this question:

extension UIView {
    func pb_takeSnapshot() -> UIImage {
        UIGraphicsBeginImageContextWithOptions(bounds.size, false, UIScreen.mainScreen().scale)
        drawViewHierarchyInRect(self.bounds, afterScreenUpdates: true)
        let image = UIGraphicsGetImageFromCurrentImageContext()
        UIGraphicsEndImageContext()
        return image
    }
}

Other solution:

You can also try sgwilly/RangeSlider instead, it's written in Swift and therefore you won't even need a Bridging Header.