blocks|key|2720242|text|您可以编写Swift扩展并在Objective-C代码中使用它。使用XCode+6.1.1进行了测试。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2720243|你所需要做的就是：|2720244|2720245|在Swift中创建扩展模块(从Swift+4.0.3开始需要@objc注解)|unordered-list-item|offset|length|style|CODE|2720246|2720247|Objective-C类中的|2720248|#import+"ProjectTarget-Swift.h"+(其中"ProjectTarget“表示与Swift扩展关联的XCode目标)|2720249|2720250|2720251|从Swift+extension|2720252|调用方法|2720253|entityMap^0|0|0|0|U|5|0|0|0|0|V|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|Y|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|Z|8|@]|9|@]|A|$]]|$1|D|3|-4|5|6|7|10|8|@]|9|@]|A|$]]|$1|E|3|F|5|G|7|11|8|@$H|12|I|13|J|K]]|9|@]|A|$]]|$1|L|3|-4|5|6|7|14|8|@]|9|@]|A|$]]|$1|M|3|N|5|6|7|15|8|@]|9|@]|A|$]]|$1|O|3|P|5|G|7|16|8|@$H|17|I|18|J|K]]|9|@]|A|$]]|$1|Q|3|-4|5|6|7|19|8|@]|9|@]|A|$]]|$1|R|3|-4|5|6|7|1A|8|@]|9|@]|A|$]]|$1|S|3|T|5|G|7|1B|8|@]|9|@]|A|$]]|$1|U|3|V|5|6|7|1C|8|@]|9|@]|A|$]]|$1|W|3|-4|5|6|7|1D|8|@]|9|@]|A|$]]]|X|$]]

You can write a Swift extension and use it in Objective-C code. Tested with XCode 6.1.1.
All you need to do is:
<ul>
<li>create your extension in Swift (<code>@objc</code> annotation needed since Swift 4.0.3)
</li>
<li><code>#import &quot;ProjectTarget-Swift.h&quot;</code> in your Objective-C class (where &quot;ProjectTarget&quot; represents the XCode target the Swift extension is associated with)
</li>
<li>call the methods from the Swift extension
</li>
</ul>

blocks|key|2720260|text|此解决方案适用于Swift+2.2和Swift+3。请注意，只能从Objective-C访问类的扩展(不包括结构或枚举)。|type|unstyled|depth|inlineStyleRanges|offset|length|style|BOLD|entityRanges|data|2720261|import+UIKit

extension+UIColor+{

++++//Custom+colours
++++class+func+otherEventColor()+->+UIColor+{
++++++++return+UIColor(red:0.525,+green:0.49,+blue:0.929,+alpha:1)
++++}
}|code-block|syntax|javascript|2720262|然后#在ObjC文件中导入"ProductModuleName-Swift.h"。|2720263|Swift+4|2720264|extension+UIColor+{

++++//+As+of+Swift+4.0.3,+the+@objc+annotation+is+needed+if+you+want+to+use+the+extension+in+Objective-C+files
++++@objc
++++class+func+otherEventColor()+->+UIColor+{
++++++++return+UIColor(red:0.525,+green:0.49,+blue:0.929,+alpha:1)
++++}
}|2720265|entityMap^0|8|H|0|0|2|12|0|0|7|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@$9|T|A|U|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|V|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|W|8|@$9|X|A|Y|B|C]]|D|@]|E|$]]|$1|M|3|N|5|6|7|Z|8|@$9|10|A|11|B|C]]|D|@]|E|$]]|$1|O|3|P|5|H|7|12|8|@]|D|@]|E|$I|J]]|$1|Q|3|-4|5|6|7|13|8|@]|D|@]|E|$]]]|R|$]]

This solution works for Swift 2.2 and Swift 3. Note that only extensions for classes (not for structs or enums) will be accessible from Objective-C.

<pre><code>import UIKit

extension UIColor {

 //Custom colours
 class func otherEventColor() -&gt; UIColor {
 return UIColor(red:0.525, green:0.49, blue:0.929, alpha:1)
 }
}
</code></pre>

Then #import "ProductModuleName-Swift.h" in your ObjC file.

Swift 4

<pre><code>extension UIColor {

 // As of Swift 4.0.3, the @objc annotation is needed if you want to use the extension in Objective-C files
 @objc
 class func otherEventColor() -&gt; UIColor {
 return UIColor(red:0.525, green:0.49, blue:0.929, alpha:1)
 }
}
</code></pre>

blocks|key|2720284|text|正如在其他答案中所述，在大多数情况下，导入生成的Swift报头在中运行。|type|unstyled|depth|inlineStyleRanges|offset|length|style|BOLD|entityRanges|data|2720285|一个例外情况是类别定义在桥接类型上(即扩展定义在String上，而不是NSString上)。这些类别不会自动桥接到它们的Objective-C对应物。要解决此问题，您需要使用Objective-C类型(并使用as+String在Swift代码中转换返回值)，或者为Swift和Objective-C类型定义一个扩展。|CODE|2720286|entityMap^0|Z|1|0|0|4E|O|6|Z|8|2W|9|0^^$0|@$1|2|3|4|5|6|7|K|8|@$9|L|A|M|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|N|8|@$9|O|A|P|B|C]|$9|Q|A|R|B|H]|$9|S|A|T|B|H]|$9|U|A|V|B|H]]|D|@]|E|$]]|$1|I|3|-4|5|6|7|W|8|@]|D|@]|E|$]]]|J|$]]

As covered in the other answers, importing the generated Swift header works in most cases.

An exception to this is when the category is defined on a bridged type (i.e. the extension is defined on <code>String</code> and not <code>NSString</code>). These categories will not automatically be bridged to their Objective-C counterparts. To get around this, you'll either need to use the Objective-C type (and cast the return value in your Swift code with <code>as String</code>) or define an extension for both the Swift and Objective-C types.

blocks|key|2720332|text|我发现在Swift+4.0中，我必须在我的扩展关键字前面添加@objc，以便Swift扩展方法在我正在扩展的Objc类的实例中可见。|type|unstyled|depth|inlineStyleRanges|offset|length|style|BOLD|CODE|entityRanges|data|2720333|简而言之：|2720334|文件配置设置：|2720335|CustomClass.h
CustomClass.m
CustomClassExtension.swift|code-block|syntax|javascript|2720336|在CustomClassExtension中：|2720337|@objc+extension+CustomClass
{
++++func+method1()+
++++{
++++++++...
++++}
}|2720338|在我的AppDelegate.m中：|2720339|self.customClass+=+[[CustomClass+alloc]+init];
[self.customClass+method1];|2720340|entityMap^0|4|9|L|2|U|5|0|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|Z|8|@$9|10|A|11|B|C]|$9|12|A|13|B|C]|$9|14|A|15|B|D]]|E|@]|F|$]]|$1|G|3|H|5|6|7|16|8|@]|E|@]|F|$]]|$1|I|3|J|5|6|7|17|8|@]|E|@]|F|$]]|$1|K|3|L|5|M|7|18|8|@]|E|@]|F|$N|O]]|$1|P|3|Q|5|6|7|19|8|@]|E|@]|F|$]]|$1|R|3|S|5|M|7|1A|8|@]|E|@]|F|$N|O]]|$1|T|3|U|5|6|7|1B|8|@]|E|@]|F|$]]|$1|V|3|W|5|M|7|1C|8|@]|E|@]|F|$N|O]]|$1|X|3|-4|5|6|7|1D|8|@]|E|@]|F|$]]]|Y|$]]

I found out that in Swift 4.0 I had to add <code>@objc</code> in front of my extension keyword in order for the Swift extension methods to become visible by an instance of the Objc class I was extending.

In short:

File configuration setup:

<pre><code>CustomClass.h
CustomClass.m
CustomClassExtension.swift
</code></pre>

In CustomClassExtension:

<pre><code>@objc extension CustomClass
{
 func method1() 
 {
 ...
 }
}
</code></pre>

In my AppDelegate.m:

<pre><code>self.customClass = [[CustomClass alloc] init];
[self.customClass method1];
</code></pre>

blocks|key|145028|text|在objective-c文件中导入"#import+"ProductModuleName-Swift.h"头文件，并在swift文件中将@objc添加到您的扩展前面。它将在swift+4.2和swift+5中正常工作|type|unstyled|depth|inlineStyleRanges|offset|length|style|BOLD|entityRanges|data|145029|entityMap^0|H|10|1W|5|26|2|0^^$0|@$1|2|3|4|5|6|7|H|8|@$9|I|A|J|B|C]|$9|K|A|L|B|C]|$9|M|A|N|B|C]]|D|@]|E|$]]|$1|F|3|-4|5|6|7|O|8|@]|D|@]|E|$]]]|G|$]]

Import "#import "ProductModuleName-Swift.h" header in objective-c file and add @objc infront of your extentsion in swift file. It will working fine in swift 4.2 and swift 5

blocks|key|145034|text|如果您认为您已经正确配置了所有内容(使用@objcMembers或@objc标记您的Swift实体，导入桥接头"ProductModuleName-Swift.h“等等)-但仍然收到No+visible+@interface+for+'FooClass'+declares+the+selector+'fooSelector'错误：|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|145035|如果您在桥接头中看到您的接口，请通过ctrl+%2B+cmd单击它来进行检查。如果你没有，看看我对这个问题的回答：Swift+to+Objective-C+header+does+not+contain+Swift+classes|BOLD|145036|entityMap|0|LINK|mutability|MUTABLE|url|https://stackoverflow.com/questions/24086595/swift-to-objective-c-header-does-not-contain-swift-classes/63902651#63902651^0|2J|20|0|I|A|Y|27|1J|1M|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@$9|R|A|S|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|T|8|@$9|U|A|V|B|C]|$9|W|A|X|B|H]]|D|@$9|Y|A|Z|1|10]]|E|$]]|$1|I|3|-4|5|6|7|11|8|@]|D|@]|E|$]]]|J|$K|$5|L|M|N|E|$O|P]]]]

If think you have configured everything correctly (marked your Swift entities with @objcMembers or @objc, imported the bridging header &quot;ProductModuleName-Swift.h&quot; and so on) – but still getting the <code>No visible @interface for 'FooClass' declares the selector 'fooSelector'</code> error:
Check if you see your interfaces in the bridging header by <code>ctrl + cmd</code> clicking on it. If you don't, check out my answer to this question: <a href="https://stackoverflow.com/questions/24086595/swift-to-objective-c-header-does-not-contain-swift-classes/63902651#63902651">Swift to Objective-C header does not contain Swift classes</a>

I searched some posts, I think I cannot write an extension under Swift, and call it from Objective-C code, right?
<code>@objc</code> like attributes only support methods, class, protocols ?

Can Objective-C code call Swift class extensions?

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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我搜索了一些帖子，我想我不能在Swift下写一个扩展，然后从Objective-C代码中调用它，对吧？像@objc这样的属性只支持方法、类、协议？

问Objective-C代码可以调用Swift类扩展吗？
EN

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问Objective-C代码可以调用Swift类扩展吗？EN