Swift 2.0代码可在Xcode中使用，但不能在Playground中使用 [英] Swift 2.0 code works in Xcode but not in Playground

问题描述

我正在学习Swift，对试图弄清如何无法加载文件感到沮丧.事实证明，该代码可在Xcode中工作，但不能在游乐场中工作.是什么原因呢?

I'm learning Swift and have been frustrated trying to figure out how I'm unable to load files. It turns out that the code works in Xcode but does not work in a playground. What is the reason for this?

代码如下:

func testFileLoad(){
    let myFilePath: String = "/Users/clay/Desktop/test.txt"
    let t: Bool = NSFileManager.defaultManager().fileExistsAtPath(myFilePath)
    print(t)

    let s: String = try! String(contentsOfFile: myFilePath, encoding: NSUTF8StringEncoding)
    print(s)

    do {
        let p: String = try String(contentsOfFile: myFilePath, encoding: NSUTF8StringEncoding)
        print(p)
    } catch {
        print("nope")
    }
}

在Xcode的测试模块中运行，它可以正常工作，并将我希望的内容输出到控制台.

Running in a test module in Xcode, it works properly and prints what I would hope for to the console.

Test Suite 'Selected tests' started at 2015-08-05 14:24:15.977 
Test Suite 'swiftgraphTests' started at 2015-08-05 14:24:15.978 
Test Case '-[swiftgraphTests.swiftgraphTests testFileLoad]' started. 
true 
this is a test 
this is a test 
Test Case '-[swiftgraphTests.swiftgraphTests testFileLoad]' passed (0.001 seconds). 
Test Suite 'swiftgraphTests' passed at 2015-08-05 14:24:15.979.      
    Executed 1 test, with 0 failures (0 unexpected) in 0.001 (0.001) seconds 
Test Suite 'Selected tests' passed at 2015-08-05 14:24:15.979.   
    Executed 1 test, with 0 failures (0 unexpected) in 0.001 (0.002) seconds

在操场上，我得到了:

我在这里做错了什么?我在操场上使用不当吗?

What am I doing wrong here? Am I using the playground improperly?

推荐答案

如果转到菜单

查看"->调试区域"->显示调试区域"

"View" -> "Debug Area" -> "Show Debug Area"

您将看到完整的错误:您没有从Playground *访问文件系统的权限."

you will see the full error: "you don't have permissions to access the filesystem from the Playground*."

解决方法是使用项目浏览器将文件包含在游乐场中.

The workaround is to include the file in the Playground using its Project Navigator.

转到菜单

查看"->导航器"->显示项目导航器"

"View" -> "Navigators" -> "Show Project Navigator"

然后将文件拖放到资源"文件夹中.

then drag and drop your file into the "Resources" folder.

然后使用NSBundle获取路径.

Then use NSBundle to get the path.

func testFileLoad() {

    // get the file path for the file from the Playground's Resources folder
    guard let path = NSBundle.mainBundle().pathForResource("test", ofType: "txt") else {
            print("Oops, the file is not in the Playground")
            return
    }

    // keeping the examples from your question
    let s: String = try! String(contentsOfFile: path, encoding: NSUTF8StringEncoding)
    print(s)

    do {
        let p: String = try String(contentsOfFile: path, encoding: NSUTF8StringEncoding)
        print(p)
    } catch {
        print("nope")
    }

}

testFileLoad()

*实际上，您只能访问包含您的Playground共享数据的/var/文件夹，而Playground只是提供了一个快捷方式.游乐场导航器中的该文件夹实际上代表/var/文件夹，并且对于每个游乐场都是唯一的.您可以通过NSBundle查看其地址:

*Actually you have only access to the /var/ folder containing your Playground shared data, and the Playground is just offering a shortcut. This folder in the Playground's navigator actually represents the /var/ folder, and is unique for each Playground. You can see its address with NSBundle:

NSBundle.mainBundle().resourcePath

这篇关于Swift 2.0代码可在Xcode中使用，但不能在Playground中使用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！