Can't Get iOS Print Renderer to Draw Properly

Question

OK. There seems to be a dearth of examples on this, and I am fairly stumped.

I'm trying to make a custom print page renderer; the type that completely customizes the output, not one that uses an existing view.

The really weird thing, is that I was able to do this in ObjC a couple of years ago, and I can't seem to do the same thing in Swift.

I should mention that I am using the prerelease (Beta 5) of Xcode, and Swift 4 (Which has almost no difference at all from Swift 3, in my project).

The project is here.

It's a completely open-source project, so nothing's hidden; however, it's still very much under development, and is a moving target.

This is the page renderer class.

BTW: Ignore the delegate class. I was just thrashing around, trying to figure stuff up. I'm not [yet] planning on doing any delegate stuff. In particular, my question concerns what's happening here:

override func drawContentForPage(at pageIndex: Int, in contentRect: CGRect) {
    let perMeetingHeight: CGFloat = self.printableRect.size.height / CGFloat(self.actualNumberOfMeetingsPerPage)
    let startingPoint = max(self.maxMeetingsPerPage * pageIndex, 0)
    let endingPointPlusOne = min(self.maxMeetingsPerPage, self.actualNumberOfMeetingsPerPage)
    for index in startingPoint..<endingPointPlusOne {
        let top = self.printableRect.origin.y + (CGFloat(index) * perMeetingHeight)
        let meetingRect = CGRect(x: self.printableRect.origin.x, y: top, width: self.printableRect.size.width, height: perMeetingHeight)
        self.drawMeeting(at: index, in: meetingRect)
    }
}

and here:

func drawMeeting(at meetingIndex: Int, in contentRect: CGRect) {
    let myMeetingObject = self.meetings[meetingIndex]
    var top: CGFloat = contentRect.origin.y
    let topLabelRect = CGRect(x: contentRect.origin.x, y: 0, width: contentRect.size.width, height: self.meetingNameHeight)
    top += self.meetingNameHeight
    let meetingNameLabel = UILabel(frame: topLabelRect)
    meetingNameLabel.backgroundColor = UIColor.clear
    meetingNameLabel.font = UIFont.boldSystemFont(ofSize: 30)
    meetingNameLabel.textAlignment = .center
    meetingNameLabel.textColor = UIColor.black
    meetingNameLabel.text = myMeetingObject.name
    meetingNameLabel.draw(topLabelRect)
}

Which is all called from here:

@IBAction override func actionButtonHit(_ sender: Any) {
    let sharedPrintController = UIPrintInteractionController.shared
    let printInfo = UIPrintInfo(dictionary:nil)
    printInfo.outputType = UIPrintInfoOutputType.general
    printInfo.jobName = "print Job"
    sharedPrintController.printPageRenderer = BMLT_MeetingSearch_PageRenderer(meetings: self.searchResults)
    sharedPrintController.present(from: self.view.frame, in: self.view, animated: false, completionHandler: nil)
}

What's going on, is that everything on a page is being piled at the top. I am trying to print a sequential list of meetings down a page, but they are all getting drawn at the y=0 spot, like so:

This should be a list of meeting names, running down the page.

The way to get here, is to start the app, wait until it's done connecting to the server, then bang the big button. You'll get a list, and press the "Action" button at the top of the screen.

I haven't bothered to go beyond the preview, as that isn't even working. The list is the only one I have wired up right now, and I'm just at the stage of simply printing the meeting names to make sure I have the basic layout right.

Which I obviously don't.

Any ideas?

Answer 1

All right. I figured out what the issue was.

I was trying to do this using UIKit routines, which assume a fairly high-level drawing context. The drawText(in: CGRect) thing was my lightbulb.

I need to do everything using lower-level, context-based drawing, and leave UIKit out of it.

Here's how I implement the drawMeeting routine now (I have changed what I draw to display more relevant information). I'm still working on it, and it will get larger:

func drawMeeting(at meetingIndex: Int, in contentRect: CGRect) {
    let myMeetingObject = self.meetings[meetingIndex]
    var remainingRect = contentRect

    if (1 < self.meetings.count) && (0 == meetingIndex % 2) {
        if let drawingContext = UIGraphicsGetCurrentContext() {
            drawingContext.setFillColor(UIColor.black.withAlphaComponent(0.075).cgColor)
            drawingContext.fill(contentRect)
        }
   }

    var attributes: [NSAttributedStringKey : Any] = [:]
    attributes[NSAttributedStringKey.font] = UIFont.italicSystemFont(ofSize: 12)
    attributes[NSAttributedStringKey.backgroundColor] = UIColor.clear
    attributes[NSAttributedStringKey.foregroundColor] = UIColor.black

    let descriptionString = NSAttributedString(string: myMeetingObject.description, attributes: attributes)
    let descriptionSize = contentRect.size
    var stringRect = descriptionString.boundingRect(with: descriptionSize, options: [NSStringDrawingOptions.usesLineFragmentOrigin,NSStringDrawingOptions.usesFontLeading], context: nil)
    stringRect.origin = contentRect.origin
    descriptionString.draw(at: stringRect.origin)

    remainingRect.origin.y -= stringRect.size.height
}