无法删除 CAShapeLayer [英] Unable to remove CAShapeLayer

问题描述

我在屏幕上总共绘制了 21 条线用于测量工具.线条在 UIViewController.view 上绘制为一个图层.我正在尝试按如下方式删除这些行.NSLog 语句确认我得到了我正在寻找的所有 21 个 CAShapeLayers.

I have a total of 21 lines drawn across the screen for a measurement tool. The lines are drawn as a layer on UIViewController.view. I am attempting to remove the lines as follows. The NSLog statement confirms that I am getting all 21 CAShapeLayers that I am looking for.

CAShapeLayer* layer = [[CAShapeLayer alloc]init];
    for (UIView *subview in viewsToRemove){
        if([subview isKindOfClass:[CAShapeLayer class]]){
            count++;
            NSLog(@"%d: %@", count, subview);
            [layerArray addObject:layer];
        }
    }
    for(CAShapeLayer *l in layerArray){
        [l removeFromSuperlayer];
    }

如果您能帮助删除这些行，我们将不胜感激.

Any help getting these lines removed would be greatly appreciated.

我认为没有必要，但如果您想在此处查看绘制线条的代码:

I don't think it's necessary but if you want to see the code to draw the lines here it is:

for(int i = 0; i < numberOfColumns; i++){
    CAShapeLayer *lineShape = nil;
    CGMutablePathRef linePath = nil;
    linePath = CGPathCreateMutable();
    lineShape = [CAShapeLayer layer];
    if(i == 0 || i == 20 || i == 10 || i == 3 || i == 17)
        lineShape.lineWidth = 4.0f;
    else
        lineShape.lineWidth = 2.0f;
    lineShape.lineCap = kCALineCapRound;
    if( i == 0 || i == 20)
        lineShape.strokeColor = [[UIColor whiteColor]CGColor];
    else if(i == 3 || i == 17)
        lineShape.strokeColor = [[UIColor redColor]CGColor];
    else if (i == 10)
        lineShape.strokeColor = [[UIColor blackColor]CGColor];
    else
        lineShape.strokeColor = [[UIColor grayColor]CGColor];

    x += xIncrement;  y = 5;


    int toY = screenHeight - self.toolBar.frame.size.height - 10;
    CGPathMoveToPoint(linePath, NULL, x, y);
    CGPathAddLineToPoint(linePath, NULL, x, toY);
    lineShape.path = linePath;
    CGPathRelease(linePath);
    [self.view.layer addSublayer:lineShape];

推荐答案

你的代码毫无意义:

CAShapeLayer* layer = [[CAShapeLayer alloc]init];
for (UIView *subview in viewsToRemove){
    if([subview isKindOfClass:[CAShapeLayer class]]){
        count++;
        NSLog(@"%d: %@", count, subview);
        [layerArray addObject:layer];
    }
}
for(CAShapeLayer *l in layerArray){
    [l removeFromSuperlayer];
}

您正在创建一个全新的 CAShapeLayer，然后将相同的 CAShapeLayer(即您的 layer 对象)一遍又一遍地添加到 layerArray.它永远不会在界面中，它永远不会有一个超层，因此将它从它的超层中移除没有任何作用.

You are creating a completely new CAShapeLayer and then adding that same CAShapeLayer (namely your layer object) over and over to the layerArray. It is never in the interface, it never has a superlayer, and so removing it from its superlayer does nothing.

此外，这条线毫无意义:

Moreover, this line is pointless:

if([subview isKindOfClass:[CAShapeLayer class]]){

子视图永远将成为 CAShapeLayer.一个子视图是一个 UIView.它不是任何类型的层(尽管它有一层).

A subview will never be a CAShapeLayer. A subview is a UIView. It is not a layer of any kind (though it has a layer).

您想要的是寻找已经在界面中的 CAShapeLayers.当然，一个简单的方法是在创建它时保留对每个 CAShapeLayer 的引用，并首先将其放入界面:

What you want to is look for the CAShapeLayers that are already in the interface. Of course, an easy way to do this would have been to keep a reference to each CAShapeLayer at the time you created it and put it into the interface in the first place:

[self.view.layer addSublayer:lineShape];
// now store a reference to this layer in an array that you can use later!

这篇关于无法删除 CAShapeLayer的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！