Swift-设置CALayer边界或框架不起作用 [英] Swift - Setting CALayer bounds or frame not working

问题描述

我是Swift的新手，我似乎无法弄清最基本的事情之一-为CALayer设置框架和界限，所以我以后可以阅读它们.

I'm new to Swift, and I can't seem to figure out one of the most basic things - setting frame and bounds for a CALayer, so I can read them later.

我试图查看在CALayer上绘制一个框的位置，以确定它与图层中心的距离有多近.

I'm trying to see where a box is drawn on a CALayer to determine how close to the center of the layer it is.

我应该假定CALayer的大小与添加到子视图中的图层/视图的大小相同，但是当我查看CALayer的帧或边界时，它的大小为零.超级视图层/视图也是如此.

I would have assumed the CALayer is the same size of the layer/view it's added to with subview, but when I look at the CALayer's frame or bounds it's zero. Same for the superview layer/view.

任何帮助将不胜感激！

目标:检查框在图层中的写入位置

Goal: check where a box is written within a layer

伪代码:

create new layer
draw a box on layer
look at box dimensions and compare to layer dimensions
if box near middle of the layer then print success

视图/层层次结构(从上到下)

View/Layer Hierarchy (top to bottom)

 1. CALayer named shapeLayer
 2. CALayer named previewLayer (this is a AVCaptureVideoPreviewLayer)
 3. UIView named videoPreview

我无法为3个视图/图层中的任何一个设置框架或边界.当我读取frame或bounds值时，我得到的只是0.

I can't set frame or bounds for any of the 3 views/layers. All i get is 0 back when I read the frame or bounds value.

注意，我也尝试过在viewWillAppear中调用代码，但结果相同.

Note, I've tried calling code in viewWillAppear as well, but same result.

override func viewDidLoad() {
    super.viewDidLoad()
    if let previewLayer = self.videoCapture.previewLayer {
        self.videoPreview.layer.addSublayer(previewLayer)
        videoCapture.previewLayer?.frame = videoPreview.bounds
    }

    if videoCapture.previewLayer?.frame != nil {

        videoCapture.previewLayer!.frame = CGRect(x:0, y:0, width:375, height: 667)

        let w = videoCapture.previewLayer!.frame.height
        let h = videoCapture.previewLayer!.frame.width

        NSLog("Print the height and width  w:%i, h:%i", w, h);

    }   
}

推荐答案

当视图对子视图进行布局时，您将获得图层的框架:

You will get the frame of your layers when the view did layout its subviews:

override func viewDidLoad() {
    super.viewDidLoad()
    if let previewLayer = self.videoCapture.previewLayer {
        self.videoPreview.layer.addSublayer(previewLayer)
    }
}

override func viewDidLayoutSubviews() {
    super.viewDidLayoutSubviews()
    if let previewLayer = self.videoCapture.previewLayer {
        videoCapture.previewLayer?.frame = videoPreview.bounds
    }

    if videoCapture.previewLayer?.frame != nil {

        videoCapture.previewLayer!.frame = CGRect(x:0, y:0, width:375, height: 667)

        let w = videoCapture.previewLayer!.frame.height
        let h = videoCapture.previewLayer!.frame.width

        NSLog("Print the height and width  w:%i, h:%i", w, h)
    }
}

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