用Swift在Cocoa上绘图会产生一个错误

When trying to draw just like in an iOS application we faced a problem. After hours of search with no luck, we decided to ask here.

当我们试图像在iOS应用程序中那样绘制时，我们遇到了一个问题。经过几个小时的搜寻，运气不好，我们决定在这里问一下。

To make a drawing we created a class as

为了绘制一个图，我们创建了一个类。

import Cocoa

class DrawImageHolder: NSView {
  override func drawRect(dirtyRect: NSRect) {
        super.drawRect(dirtyRect)
       print(" drawRect is executed  ")

       // drawing code 
  }
}

then we connected the class to a NSView like this

然后我们将类连接到NSView

But we have received

但是我们已经收到

-[NSApplication runModalForWindow:] may not be invoked inside of transaction commit (usually this means it was invoked inside of a view's -drawRect: method.) The modal dialog has been suppressed to avoid deadlock.

-[NSApplication runModalForWindow:]不能在事务提交内部调用(通常这意味着它在视图的- drawrect:方法内部调用)。模态对话框已被抑制以避免死锁。

message from console instead of drawing.

来自控制台的消息，而不是绘图。

Besides the print(" drawRect is executed ") was not executed.

此外，打印(“drawRect被执行”)没有被执行。

Most probably we are forgetting something simple.

很可能我们忘记了一些简单的事情。

1 个解决方案

#1

Your class inherits from NSView:

类继承自NSView:

class DrawImageHolder: NSView

So the print you're using:

所以你使用的打印:

print(" drawRect is executed  ")

is actually NSView's print. The view tries to show a dialog for printing, and as the error states, it does from a place it shouldn't.

实际上是NSView打印。视图试图显示一个用于打印的对话框，当错误发生时，它会在不应该显示的地方显示。

The solution is to prefix print with Swift so that you're explicitly using Swift's print instead of NSView's print:

解决方案是使用Swift的前缀打印，这样您就可以明确地使用Swift的打印而不是NSView的打印:

class DrawImageHolder: NSView {
  override func drawRect(dirtyRect: NSRect) {
       super.drawRect(dirtyRect)
       Swift.print(" drawRect is executed  ")
  }
}

#1