在我的情况下，我已经导入桥接头丢失的文件。在我删除错误导入后，错误通知消失了。

当此错误开始弹出时，只需注释掉您编写的最后/最近的一段代码并等待一段时间。语法高亮显示应该会重新出现。这就是我解决这个问题的方法。

    func someFunc() -> (Int?, Int?, Int?) {
     var retVal1:Int? = nil
     var retVal2:Int? = nil
     var retVal3:Int? = nil

     //some other code

     //commenting out the line below helped me
     //(retVal1, retVal2, retVal3)
     return (retVal1, retVal2, retVal3)
    }

Xcode 6.1 Beta 3:

一旦你在一个Swift文件中定义了一个非私有类型别名(例如typealias Foo = Int)，在另一个文件中输入字母c, SourceKitService就会崩溃。

解决方案是要么放弃使用类型别名，等待下一个beta版本，要么将类型别名包装在类定义中:

public class DummyClass {
    public typealias Foo = String
}

像这样使用它:

var myVar:DummyClass.Foo?

我在苹果的开发者论坛上找到了一个解决方案(需要登录，所以我也会在这里解释)。

TLDR:不要在Objective-C中导入与@interface同名的@protocol到Swift桥接头。例如，Facebook SDK有一个名为“FBGraphObject”的协议和接口。

以下是论坛帖子:

Adding Facebook SDK causes SourceKitService to crash. If you want to use beta 3 and you need Facebook SDK, one work around that I found and is working for me is refactoring Facebook SDK's @protocol FBGraphObject and renaming it to something like @protocol FBGraphObjectProtocol as an @interface FBGraphObject also exists and apparently SourceKit doesn't like it. It sure is a temporary solution just to keep you functional and you'll have to use Cocoapods or otherwise build Facebook SDK yourself rather than using the framework library. For the time being, you'll need to make sure you don't have conflicting @protocol and @interface declarations and that includes 3rd party libraries you may be using. This cost me today, hope it helps! Posted by e.parto on July 10, 2014

我发现从终端删除派生数据可以解决这个问题，直到下一次崩溃。:年代

它位于:/Users/{用户名}/Library/Developer/Xcode/DerivedData/{项目名}-{随机字符序列}

我希望这能有所帮助。

为了解决这个问题，你的Swift代码可能会有一些奇怪的问题。例如，因为您正在复制和粘贴，所以有多个iboutlet的定义。通常这只是一个无法处理的语法错误。