NSView初始化：-init：vs. -awakeFromNib： [英] NSView initialization: -init: vs. -awakeFromNib:

问题描述

我有一个简单的类 MyView 继承自 NSView 和实例变量 NSImage * image ; 中。类功能是在视图上绘制图像。

但是，在 -drawRect：图像实例总是等于 nil ，如果它在 -init：函数中初始化而不是 nil 如果它在 -awakeFromNib：中初始化。日志显示 -init：和 -awakeFromNib：函数只调用一次。

-awakeFromNib：默认重新初始化GUI组件

解决方案

否。对于 awakeFromNib 没有默认实现。

您的问题是您覆盖了错误的初始化方法。 NSView 的指定的初始化器是 initWithFrame：。你的子类的简单 init 永远不会被调用，这就是为什么你的 image ivar没有指向任何东西。 p>

您可以在 awakeFromNib 或 initWithFrame中初始化ivar： 。它没有什么区别。前者在后者之后调用，它作为一个点提供，您可以插入需要与您的nib中的其他对象交互的初始化代码（通过您的 IBOutlets ）。

I have a simple class MyView inherited from NSView and instance variable NSImage * image; in it. Class functionality is to draw image on the view.

However, in -drawRect: image instance always equal nil, if it was initialized in -init: function and not nil if it was initialized in -awakeFromNib:. Log shows both -init: and -awakeFromNib: functions are called only once.

Does -awakeFromNib: reinitialize GUI component by default?

解决方案

No. There is no default implementation for awakeFromNib.

Your problem is that you're overriding the wrong initialization method. An NSView's designated initializer is initWithFrame:. Your subclass's plain init never gets called, and that is why your image ivar doesn't point to anything.

You can initialize that ivar in either awakeFromNib or initWithFrame:. It makes no difference. The former is called after the latter, and it is provided as a point where you can insert initialization code that needs to interact with other objects in your nib (via your IBOutlets).

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