条形按钮项目未在SWIFT中显示

I created a simple Bar button item in my project but it is not showing when I run it. This is how I declare it

我在项目中创建了一个简单的Bar按钮项,但是当我运行它时它没有显示。这是我如何宣布它

@IBOutlet weak var songSelectionBar: UIBarButtonItem!

@IBOutlet弱var songSelectionBar:UIBarButtonItem!

Here is a screen shot of my project. I am fairly new to swift so I know I am doing something that should be simple (or maybe not).

这是我的项目的屏幕截图。我对swift很新,所以我知道我正在做一些应该简单(或者可能不是)的事情。

Here is some more code from the project. This function returns the contents of the directory. My understanding is that I should use a tableview to display the output of this function. Can anyone point me to an example or show me how to do this? Thanks

这是项目中的一些代码。此函数返回目录的内容。我的理解是我应该使用tableview来显示这个函数的输出。任何人都可以给我一个例子或告诉我如何做到这一点?谢谢

func getMusicFilesInDirectory() -> [String] {        
    //var wavFiles:[String]
    // We need just to get the documents folder url
    let documentsUrl =  NSFileManager.defaultManager().URLsForDirectory(.DocumentDirectory, inDomains: .UserDomainMask).first!

    // now lets get the directory contents (including folders)
    do {
        let directoryContents = try NSFileManager.defaultManager().contentsOfDirectoryAtURL(documentsUrl, includingPropertiesForKeys: nil, options: NSDirectoryEnumerationOptions())
        print(directoryContents)

    } catch let error as NSError {
        print(error.localizedDescription)
    }
    // now filter the directory to extract only Wav Files

    do {
        let directoryUrls = try  NSFileManager.defaultManager().contentsOfDirectoryAtURL(documentsUrl, includingPropertiesForKeys: nil, options: NSDirectoryEnumerationOptions())
        print(directoryUrls)
        let wavFilesDir = directoryUrls.filter(){ $0.pathExtension! == "wav" }.map{ $0.lastPathComponent! }
        wavFiles = ["Wav Music Files:\n" + wavFilesDir.description]
       } catch let error as NSError {
        print(error.localizedDescription)
    }
     return wavFiles
                                       }

1 个解决方案

#1

If you just declare the IBOutlet,not drag it out from IB,you should get rid of the "weak".
The IB has a strong reference to it's IBOutlet,so you must use it's IBOutlets with weak.
By contrast,if you manually declare an IBOutlet,you must keep a strong reference to it.

如果你只是声明IBOutlet,而不是从IB中拖出它,你应该摆脱“弱”。 IB强烈引用它的IBOutlet,所以你必须使用它的弱IBOutlets。相反,如果手动声明IBOutlet,则必须对其进行强引用。