如何将符合NSCoding的对象克隆到其子类中?

问题描述

我有一个NSPopUpButtonCell的自定义子类，以便可以覆盖它的drawBezelWithFrame:inView:方法.

I have a custom subclass of NSPopUpButtonCell so that I can overwrite its drawBezelWithFrame:inView: method.

当前，我必须使用initTextCell:pullsDown:创建一个新实例，然后手动复制其所有属性.这相当乏味且容易出错，因为我可能会缺少一些属性.

Currently, I have to create a fresh instance using initTextCell:pullsDown: and then copy all its properties by hand. That's rather tedious and error-prone as I may be missing some properties.

我想知道我是否可以代替initWithCoder:来完成此任务.我想我应该能够将现有NSPopUpButtonCell实例中的数据归档到NSCoder对象中，例如到NSKeyedArchiver中，然后将该数据归档回我的NSPopUpButtonCell子类中.但是我不知道该怎么做.

I wonder if I can use initWithCoder: for this task instead. I imagine I should be able to file the data from the existing NSPopUpButtonCell instance into an NSCoder object, e.g. into NSKeyedArchiver, and then file that data back into my NSPopUpButtonCell subclass. But I can't figure out how to accomplish that.

推荐答案

好像我以前使用了错误的函数.隔离非常简单.

Looks like I just used the wrong functions before. The solition is pretty straight-forward.

此代码将NSPopUpButtonCell的属性复制到其子类中，以便我可以覆盖其draw ...方法:

This code duplicates the properties of a NSPopUpButtonCell into a subclass of it, so that I can overwrite its draw... methods:

@interface MyPopup : NSPopUpButton
@end

@implementation MyPopup
- (instancetype)initWithCoder:(NSCoder *)coder {
    self = [super initWithCoder:coder];
    if (self) {
        // Set up the archiver
        NSMutableData *data = [NSMutableData data];
        NSKeyedArchiver *arch = [[NSKeyedArchiver alloc] initForWritingWithMutableData:data];
        // Archive the cell's properties
        [self.cell encodeWithCoder:arch];
        [arch finishEncoding];
        // Set up the unarchiver
        NSKeyedUnarchiver *ua = [[NSKeyedUnarchiver alloc] initForReadingWithData:data];
        // Create a subclass of the cell's class, using the same properties
        MyCell *newCell = [[MyCell alloc] initWithCoder:ua];
        // Assign the new subclass object as the NSButton's cell.
        self.cell = newCell;
    }
    return self;
}

以下显示了使用自定义NSButtonCell子类的另一种更简洁的方法:对文本使用NSPopupButton的全宽度，没有箭头

Another, cleaner, way to use a custom NSButtonCell subclass is shown here: Using full width of NSPopupButton for text, no arrows

这篇关于如何将符合NSCoding的对象克隆到其子类中?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！