使用xib创建可重用的UIView（并从storyboard加载） [英] Creating a reusable UIView with xib (and loading from storyboard)

问题描述

好的，StackOverflow上有很多关于此的帖子，但没有一个在解决方案上特别清楚。我想用附带的xib文件创建一个自定义 UIView 。要求是：

OK, there are dozens of posts on StackOverflow about this, but none are particularly clear on the solution. I'd like to create a custom UIView with an accompanying xib file. The requirements are:

• 没有单独的 UIViewController - 一个完全独立的类


• 允许我设置/获取视图属性的类中的插座

• No separate UIViewController – a completely self-contained class
• Outlets in the class to allow me to set/get properties of the view

我的当前这样做的方法是：

My current approach to doing this is:

1. 覆盖 - （id）initWithFrame：

-(id)initWithFrame:(CGRect)frame {
    self = [[[NSBundle mainBundle] loadNibNamed:NSStringFromClass([self class])
                                          owner:self
                                        options:nil] objectAtIndex:0];
    self.frame = frame;
    return self;
}

使用以编程方式实例化 - （id）我的视图控制器中的initWithFrame：

MyCustomView *myCustomView = [[MyCustomView alloc] initWithFrame:CGRectMake(0, 0, self.view.bounds.size.width, self.view.bounds.size.height)];
[self.view insertSubview:myCustomView atIndex:0];

此工作正常（尽管从不调用 [super init] 并且只是使用加载的nib的内容设置对象似乎有点怀疑 - 这里有建议在这种情况下添加一个子视图也可以正常工作）。但是，我希望能够从故事板中实例化视图。所以我可以：

This works fine (although never calling [super init] and simply setting the object using the contents of the loaded nib seems a bit suspect – there is advice here to add a subview in this case which also works fine). However, I'd like to be able to instantiate the view from the storyboard also. So I can:

1. 在故事板中的父视图上放置 UIView / li>
   
2. 将自定义类设置为 MyCustomView



3. 覆盖 - （id）initWithCoder： - 我见过的代码最常适用于以下模式：

1. Place a UIView on a parent view in the storyboard
2. Set its custom class to MyCustomView

3. Override -(id)initWithCoder: – the code I've seen the most often fits a pattern such as the following:

-(id)initWithCoder:(NSCoder *)aDecoder {
    self = [super initWithCoder:aDecoder];
    if (self) {
        [self initializeSubviews];
    }
    return self;
}

-(id)initWithFrame:(CGRect)frame {
    self = [super initWithFrame:frame];
    if (self) {
        [self initializeSubviews];
    }
    return self;
}

-(void)initializeSubviews {
    typeof(view) view = [[[NSBundle mainBundle]
                         loadNibNamed:NSStringFromClass([self class])
                                owner:self
                              options:nil] objectAtIndex:0];
    [self addSubview:view];
}

当然，这个不起作用，因为我是否使用上面的方法，或者我是否以编程方式实例化，在输入 - （id）initWithCoder： > - （void）initializeSubviews 并从文件中加载nib。

Of course, this doesn't work, as whether I use the approach above, or whether I instantiate programatically, both end up recursively calling -(id)initWithCoder: upon entering -(void)initializeSubviews and loading the nib from file.

其他一些SO问题涉及此问题，例如这里， here ， here 和此处。但是，没有给出令人满意的答案解决问题：

Several other SO questions deal with this such as here, here, here and here. However, none of the answers given satisfactorily fixes the problem:

• 一个常见的建议似乎是将整个类嵌入到UIViewController中，在那里加载nib，但这对我来说似乎不是最理想的，因为它需要添加另一个文件作为包装器

任何人都可以给出建议如何解决这个问题，并在自定义 UIView 中获得工作网点，并且最小化/没有瘦控制器包装？或者是否有另一种更清洁的方法来处理最少的样板代码？

Could anyone give advice on how to resolve this problem, and get working outlets in a custom UIView with minimum fuss/no thin controller wrapper? Or is there an alternative, cleaner way of doing things with minimum boilerplate code?

推荐答案

您的问题是调用 loadNibNamed：来自（后代） initWithCoder：。 loadNibNamed：在内部调用 initWithCoder：。如果你想覆盖storyboard编码器，并且总是加载你的xib实现，我建议采用以下技术。向视图类添加属性，并在xib文件中将其设置为预定值（在用户定义的运行时属性中）。现在，在调用 [super initWithCoder：aDecoder]; 之后，检查属性的值。如果是预定值，请不要调用 [self initializeSubviews]; 。

Your problem is calling loadNibNamed: from (a descendant of) initWithCoder:. loadNibNamed: internally calls initWithCoder:. If you want to override the storyboard coder, and always load your xib implementation, I suggest the following technique. Add a property to your view class, and in the xib file, set it to a predetermined value (in User Defined Runtime Attributes). Now, after calling [super initWithCoder:aDecoder]; check the value of the property. If it is the predetermined value, do not call [self initializeSubviews];.

所以，像这样：

-(instancetype)initWithCoder:(NSCoder *)aDecoder {
    self = [super initWithCoder:aDecoder];

    if (self && self._xibProperty != 666)
    {
        //We are in the storyboard code path. Initialize from the xib.
        self = [self initializeSubviews];

        //Here, you can load properties that you wish to expose to the user to set in a storyboard; e.g.:
        //self.backgroundColor = [aDecoder decodeObjectOfClass:[UIColor class] forKey:@"backgroundColor"];
    }

    return self;
}

-(instancetype)initializeSubviews {
    id view =   [[[NSBundle mainBundle] loadNibNamed:NSStringFromClass([self class]) owner:self options:nil] firstObject];

    return view;
}

这篇关于使用xib创建可重用的UIView（并从storyboard加载）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！