Swift 2.0代码适用于Xcode,但不适用于Playground

Question

我正在学习Swift并且一直在试图弄清楚我无法加载文件.事实证明,代码在Xcode中工作,但在操场上不起作用.这是什么原因？

这是代码:

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,它可以正常工作并打印我希望的控制台.

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,我明白了:

我在这做错了什么？我不正确地使用操场吗？

Answer 1

如果你去菜单

"查看" - >"调试区" - >"显示调试区"

您将看到完整错误:"您无权从Playground*访问文件系统."

解决方法是使用Project Navigator将文件包含在Playground中.

转到菜单

"查看" - >"导航器" - >"显示项目导航器"

然后将文件拖放到"Resources"文件夹中.

然后使用NSBundle获取路径.

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/var/包含Playground共享数据的文件夹,而Playground只提供快捷方式.Playground导航器中的此文件夹实际上代表/var/文件夹,并且对于每个Playground都是唯一的.您可以使用NSBundle查看其地址:

NSBundle.mainBundle().resourcePath