blocks|key|313670|text|为什么需要复制语义？UIImage是不可变的，因此设置复制策略没有任何好处。如果有其他人可能修改您的镜像的风险，您只需要一个复制策略。因为UIImage是不可变的，所以没有发生这种情况的风险，所以保留属性就可以了。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|313671|如果你多解释一下你正在尝试做什么，可能会有其他方法来实现它。|313672|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|F|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|G|8|@]|9|@]|A|$]]|$1|D|3|-4|5|6|7|H|8|@]|9|@]|A|$]]]|E|$]]

<p>Why do you need copy semantics? The UIImage is immutable, so there's no benefit to setting a copy policy. You just need a copy policy if there's the risk that someone else could modify the image on you. Since the UIImage is immutable, there's no risk of that happening, so a retain property is fine.</p>

<p>If you explain a bit more what you're trying to do, it might be that there's some other way of achieving it.</p>


blocks|key|313677|text|以下是一种方法：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|313678|UIImage+*imageToCopy+=+<#+Your+image+here+#>;
UIGraphicsBeginImageContext(imageToCopy.size);
[imageToCopy+drawInRect:CGRectMake(0,+0,+imageToCopy.size.width,+imageToCopy.size.height)];
UIImage+*copiedImage+=+[UIGraphicsGetImageFromCurrentImageContext()+retain];
UIGraphicsEndImageContext();+++|code-block|syntax|javascript|313679|我需要这样做的原因是，我用imageWithContentsOfFile:初始化了一个图像变量，并且我希望能够从磁盘中删除该文件，但保留该图像变量。我惊讶地发现，当文件被删除时，image变量变得疯狂。它显示奇怪的随机数据，即使它是在文件被删除之前初始化的。当我首先进行深度复制时，它工作得很好。|313680|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|L|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|M|8|@]|9|@]|A|$]]|$1|I|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|J|$]]

<p>Here is a way to do it:</p>

<pre><code>UIImage *imageToCopy = &lt;# Your image here #&gt;;
UIGraphicsBeginImageContext(imageToCopy.size);
[imageToCopy drawInRect:CGRectMake(0, 0, imageToCopy.size.width, imageToCopy.size.height)];
UIImage *copiedImage = [UIGraphicsGetImageFromCurrentImageContext() retain];
UIGraphicsEndImageContext();   
</code></pre>

<p>The reason I needed this is that I had an image variable initialized with imageWithContentsOfFile:, and I wanted to be able to delete the file from disk but keep the image variable. I was surprised to find that when the file is deleted the image variable goes crazy. It was displaying wacky random data even though it was initialized before the file was deleted. When I deep copy first it works fine.</p>


blocks|key|313690|text|因为图像本身是一个指针，所以您需要创建一个图像上下文，将图像绘制到上下文中，然后从上下文中获取原始图像。也许你需要使用UIImage.CGImage。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|313691|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|D|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|E|8|@]|9|@]|A|$]]]|C|$]]

<p>Because the image itself is a pointer,  you need to create an image context, draw the image into the context, and then get the original image from the context. Maybe you need to use the UIImage.CGImage.</p>


blocks|key|5327269|text|+CGImageRef+newCgIm+=+CGImageCreateCopy(oldImage.CGImage);
+UIImage+*newImage+=+[UIImage+imageWithCGImage:newCgIm+scale:oldImage.scale+
+++++++++++++++++++++orientation:oldImage.imageOrientation];|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|5327270|unstyled|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|G|8|@]|9|@]|A|$B|C]]|$1|D|3|-4|5|E|7|H|8|@]|9|@]|A|$]]]|F|$]]

<pre><code> CGImageRef newCgIm = CGImageCreateCopy(oldImage.CGImage);
 UIImage *newImage = [UIImage imageWithCGImage:newCgIm scale:oldImage.scale 
                     orientation:oldImage.imageOrientation];
</code></pre>


blocks|key|5327301|text|一份深拷贝|type|unstyled|depth|inlineStyleRanges|entityRanges|data|5327302|当谈到深度复制时，我们必须首先理解UIImage是一个容器。它实际上并不包含图像数据。底层数据可以是CIImage或CGImage。在大多数情况下，支持数据是一个CGImage，而后者又是一个包装结构，复制CGImage只是复制元数据，而不是底层数据。如果想要复制底层数据，可以将图像绘制到上下文中，或者以PNG格式获取数据的副本。|offset|length|style|CODE|5327303|UIImagePNGRepresentation|5327304|使用以下代码创建一个游乐场演示了该方法。|5327305|let+zebra+=+UIImage(named:+"an_image_of_a_zebra")
print(zebra?.CGImage)+//+check+the+address
let+shallowZebra+=+UIImage(CGImage:+zebra!.CGImage!)+
print(shallowZebra.CGImage!)+//+same+address

let+zebraData+=+UIImagePNGRepresentation(zebra!)
let+newZebra+=+UIImage(data:+zebraData!)
print(newZebra?.CGImage)+//+new+address|code-block|syntax|javascript|5327306|entityMap^0|0|H|7|1E|7|1M|7|29|7|2V|7|0|0|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|T|8|@$D|U|E|V|F|G]|$D|W|E|X|F|G]|$D|Y|E|Z|F|G]|$D|10|E|11|F|G]|$D|12|E|13|F|G]]|9|@]|A|$]]|$1|H|3|I|5|6|7|14|8|@]|9|@]|A|$]]|$1|J|3|K|5|6|7|15|8|@]|9|@]|A|$]]|$1|L|3|M|5|N|7|16|8|@]|9|@]|A|$O|P]]|$1|Q|3|-4|5|6|7|17|8|@]|9|@]|A|$]]]|R|$]]

<h2>A deep copy</h2>

<p>When talking about deep copies we must first understand that <code>UIImage</code> is a container. It doesn't actually contain the image data. The underlying data can be a <code>CIImage</code> or a <code>CGImage</code>. In most cases the backing data is a <code>CGImage</code> which is in turn a wrapping struct and copying the <code>CGImage</code> is just copying the metadata and not the underlying data. If you want to copy the underlying data you can draw the image into a context or grab a copy of the data as a PNG.</p>

<h3>UIImagePNGRepresentation</h3>

<p>Creating a playground with the following demonstrates the method.</p>

<pre><code>let zebra = UIImage(named: "an_image_of_a_zebra")
print(zebra?.CGImage) // check the address
let shallowZebra = UIImage(CGImage: zebra!.CGImage!) 
print(shallowZebra.CGImage!) // same address

let zebraData = UIImagePNGRepresentation(zebra!)
let newZebra = UIImage(data: zebraData!)
print(newZebra?.CGImage) // new address
</code></pre>


blocks|key|5327323|text|Swift+5.1的代码：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|5327324|++++let+imageToCopy+=+<#+your_image+#>
++++UIGraphicsBeginImageContext(imageToCopy.size)
++++imageToCopy.draw(in:+CGRect(x:+0,+y:+0,+width:+imageToCopy.size.width,+height:+imageToCopy.size.height))
++++let+copiedImage+=+UIGraphicsGetImageFromCurrentImageContext()
++++UIGraphicsEndImageContext()|code-block|syntax|javascript|5327325|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

<p>Code for Swift 5.1:</p>

<pre><code>    let imageToCopy = &lt;# your_image #&gt;
    UIGraphicsBeginImageContext(imageToCopy.size)
    imageToCopy.draw(in: CGRect(x: 0, y: 0, width: imageToCopy.size.width, height: imageToCopy.size.height))
    let copiedImage = UIGraphicsGetImageFromCurrentImageContext()
    UIGraphicsEndImageContext()
</code></pre>


<p>My class contains an UIImage property which I want to enforce as a 'copy' property by any external clients accessing it. But, when I try to do a copy in my custom setter, I get the runtime error about UIImage not supporting copyWithZone. So what's a good way to ensure that the correct ownership policy is followed?</p>

<pre><code>// declared in the interface as:
@property (nonatomic, readonly, copy) UIImage *personImage;

// class implementation
- (void)setPersonImage:(UIImage *)newImage
{
    if (newImage != personImage) 
    {
        [personImage release];

        // UIImage doesn't support copyWithZone
        personImage = [newImage copy];
    }
}
</code></pre>


Making deep copy of UIImage

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

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我的类包含一个UIImage属性，我希望访问它的任何外部客户端都能强制执行该属性作为“复制”属性。但是，当我尝试在我的自定义setter中执行复制时，我得到关于UIImage不支持copyWithZone的运行时错误。那么，什么是确保遵循正确的所有权策略的好方法呢？// declared in the interfac...

问制作UIImage的深层拷贝
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