Question

我正在尝试在 swift Playground 中制作自定义 UIView 组件。我已经能够弄清楚如何做除了正确渲染文本之外的所有事情。我不确定我是否应该通过核心图形或核心文本来完成此操作，或者不确定如何让它正常工作。

正如您在下图中看到的，我想在自定义视图组件的两侧颠倒和正面朝上渲染文本

我已经尝试了各种方法来让文本发挥作用，但我总是搁浅。如果有人能够向我展示如何修改我的游乐场以添加一些文本渲染，那就太棒了。

游乐场代码

// Playground - noun: a place where people can play

import Foundation
import UIKit

class RunwayView : UIView {
    
    
    var northText : String?
    var southText : String?
    
    
    ///Draws the "runway"
    override func drawRect(rect: CGRect) {
        
        // Setup graphics context
        var ctx = UIGraphicsGetCurrentContext()
        
        
        // clear context
        CGContextClearRect(ctx, rect)
        let parentVieBounds = self.bounds
        let width = CGRectGetWidth(parentVieBounds)
        let height = CGRectGetHeight(parentVieBounds)
        
        
        // Setup the heights
        let endZoneHeight : CGFloat = 40
        
    
        /* Remember y is negative and 0,0 is upper left*/
        
        
        //Create EndZones
        CGContextSetRGBFillColor(ctx, 0.8, 0.8, 0.8, 1)
        CGContextFillRect(ctx, CGRectMake(0, 0, width, endZoneHeight))
        CGContextFillRect(ctx, CGRectMake(0, height-endZoneHeight, width, endZoneHeight))
        
        
        var northString = NSMutableAttributedString(string: "36")
        var attrs = [NSFontAttributeName : UIFont.systemFontOfSize(16.0)]
        var gString = NSMutableAttributedString(string:"g", attributes:attrs);
        
        
        var line = CTLineCreateWithAttributedString(gString)
        
        CGContextSetTextPosition(ctx, 10, 50);
        CTLineDraw(line, ctx);
        
        // Clean up
       
    }
    
}


var outerFrame : UIView = UIView(frame: CGRectMake(20,20,400,400))
var runway1 : RunwayView = RunwayView(frame: CGRectMake(0,0,30,260))
var runway2 : RunwayView = RunwayView(frame: CGRectMake(80,0,30,340))

runway1.transform = CGAffineTransformConcat(CGAffineTransformMakeTranslation(20, 200),
    CGAffineTransformMakeRotation(-0.785398163))
outerFrame.addSubview(runway1)

runway2.transform = CGAffineTransformConcat(CGAffineTransformMakeTranslation(120, 140),
    CGAffineTransformMakeRotation(-0.585398163))

outerFrame.addSubview(runway2)



outerFrame.backgroundColor = UIColor.yellowColor()
outerFrame.clipsToBounds = true


// View these elements
runway1
outerFrame
runway1

我为我的应用程序编写了一个实用函数来使用以下命令绘制文本CoreText。 它返回文本大小以供进一步处理：

func drawText(context: CGContextRef, text: NSString, attributes: [String: AnyObject], x: CGFloat, y: CGFloat) -> CGSize {
    let font = attributes[NSFontAttributeName] as UIFont
    let attributedString = NSAttributedString(string: text, attributes: attributes)

    let textSize = text.sizeWithAttributes(attributes)

    // y: Add font.descender (its a negative value) to align the text at the baseline
    let textPath    = CGPathCreateWithRect(CGRect(x: x, y: y + font.descender, width: ceil(textSize.width), height: ceil(textSize.height)), nil)
    let frameSetter = CTFramesetterCreateWithAttributedString(attributedString)
    let frame       = CTFramesetterCreateFrame(frameSetter, CFRange(location: 0, length: attributedString.length), textPath, nil)

    CTFrameDraw(frame, context)

    return textSize
}

像这样称呼它：

var textAttributes: [String: AnyObject] = [
    NSForegroundColorAttributeName : UIColor(white: 1.0, alpha: 1.0).CGColor,
    NSFontAttributeName : UIFont.systemFontOfSize(17)
]

drawText(ctx, text: "Hello, World!", attributes: textAttributes, x: 50, y: 50)

希望对您有帮助。