Swift 中的 iOS 内存警告

Question

我使用计时器每 0.1 秒触发一个函数重复，以使用 UIGraphicsGetImageFromCurrentImageContext 获取 UIImage 并分配给 @IBOutllet 弱 UImageView.image.(coverImageView)

var timer:Timer?

func fireTimer() {
    timer = Timer.scheduledTimer(withTimeInterval: 0.1, repeats: true, block: { [weak self] _ in
        self?.lightTheFier()
    })
}

func invalidateTimer() {
    timer?.invalidate()
    timer = nil
}

func lightTheFier() {
    var points = [CGPoint]()
    for pin in pins {
        let point = mapView.convert(pin.coordinate, toPointTo: coverImageView)
        points.append(point)
    }
    coverImageView.image = getMaskedImage(points: points, zoomLevel: Int(mapView.zoomLevel()))
}

func getOringinalImageFromPath() -> UIImage{
    UIGraphicsBeginImageContextWithOptions(coverImageView.bounds.size, false, 0.0)
    let path = UIBezierPath(rect: coverImageView.bounds)
    UIColor.black.setFill()
    path.fill()
    let image = UIGraphicsGetImageFromCurrentImageContext()
    UIGraphicsEndImageContext()
    return image!
}

func getMaskImageFromPath(points:[CGPoint], scale:CGFloat) -> UIImage {
    UIGraphicsBeginImageContextWithOptions(coverImageView.bounds.size, false, 0.0)
    let radius:CGFloat = 10.0
    UIColor.blue.setFill()
    for point in points {
        let rect = CGRect(x: point.x - (scale*radius/2), y: point.y - (scale*radius/2), width: scale*radius, height: scale*radius)
        let path = UIBezierPath(ovalIn: rect)
        path.fill()
    }
    let image = UIGraphicsGetImageFromCurrentImageContext()
    UIGraphicsEndImageContext()
    return image!
}

func getMaskedImage(points:[CGPoint], zoomLevel:Int) -> UIImage{
    let orImage = getOringinalImageFromPath().cgImage
    let maskImage = getMaskImageFromPath(points: points, scale: CGFloat(zoomLevel)).cgImage
    let mask = CGImage(maskWidth: maskImage!.width, height: maskImage!.height, bitsPerComponent: maskImage!.bitsPerComponent, bitsPerPixel: maskImage!.bitsPerPixel, bytesPerRow: maskImage!.bytesPerRow, provider: maskImage!.dataProvider!, decode: nil, shouldInterpolate: true)
    let maskRef = orImage?.masking(mask!)
    let image = UIImage(cgImage: maskRef!)
    return image
}

上面的所有代码都在 ViewController.swift 中进行测试。

函数运行过程中内存不断增加没关系，我想要的是当我使定时器无效时它可以释放内存。

我应该如何解决这个问题？

Answer 1

您正在启动一个图像上下文:UIGraphicsBeginImageContextWithOptions，但您永远不会结束它。您需要将 UIGraphicsEndImageContext() 添加到 getMaskImageFromPath 和 getOringinalImageFromPath 方法中:

func getMaskImageFromPath(points:[CGPoint], scale:CGFloat) -> UIImage {
    UIGraphicsBeginImageContextWithOptions(coverImageView.bounds.size, false, 0.0)
    let radius:CGFloat = 10.0
    UIColor.blue.setFill()
    for point in points {
        let rect = CGRect(x: point.x - (scale*radius/2), y: point.y - (scale*radius/2), width: scale*radius, height: scale*radius)
        let path = UIBezierPath(ovalIn: rect)
        path.fill()
    }
    let image = UIGraphicsGetImageFromCurrentImageContext()
    UIGraphicsEndImageContext() // Missing this line
    return image!
}