在 iOS 上编写文件答案

【问题标题】：Write a file on iOS在 iOS 上编写文件
【发布时间】：2011-08-02 22:42:55
【问题描述】：

如何在 iOS 上编写文件？我正在尝试使用以下代码执行此操作，但我做错了：

char *saves = "abcd";
NSData *data = [[NSData alloc] initWithBytes:saves length:4]; 
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDirectory = [paths objectAtIndex:0];
NSString *appFile = [documentsDirectory stringByAppendingPathComponent:@"MyFile"];
[data writeToFile:appFile atomically:YES];

我在资源上创建了 MyFile.txt。

【问题讨论】：

请准确描述发生了什么问题。

标签： ios iphone file nsbundle

【解决方案1】：

也许这对你有用。

//Method writes a string to a text file
-(void) writeToTextFile{
        //get the documents directory:
        NSArray *paths = NSSearchPathForDirectoriesInDomains
            (NSDocumentDirectory, NSUserDomainMask, YES);
        NSString *documentsDirectory = [paths objectAtIndex:0];

        //make a file name to write the data to using the documents directory:
        NSString *fileName = [NSString stringWithFormat:@"%@/textfile.txt", 
                                                      documentsDirectory];
        //create content - four lines of text
        NSString *content = @"One\nTwo\nThree\nFour\nFive";
        //save content to the documents directory
        [content writeToFile:fileName 
                         atomically:NO 
                               encoding:NSUTF8StringEncoding 
                                      error:nil];

}


//Method retrieves content from documents directory and
//displays it in an alert
-(void) displayContent{
        //get the documents directory:
        NSArray *paths = NSSearchPathForDirectoriesInDomains
                        (NSDocumentDirectory, NSUserDomainMask, YES);
        NSString *documentsDirectory = [paths objectAtIndex:0];

        //make a file name to write the data to using the documents directory:
        NSString *fileName = [NSString stringWithFormat:@"%@/textfile.txt", 
                                                      documentsDirectory];
        NSString *content = [[NSString alloc] initWithContentsOfFile:fileName
                                                      usedEncoding:nil
                                                             error:nil];
        //use simple alert from my library (see previous post for details)
        [ASFunctions alert:content];
        [content release];

}

【讨论】：

我找不到我写的文件似乎它不存在
可以更改文档目录路径。
使用 -- #define DOCUMENTS_FOLDER [NSHomeDirectory() stringByAppendingPathComponent:@"Documents"]
如果我不这样做，我的文件的默认目录是什么？
什么是 NSStringEncodingConversionAllowLossy？编码应该是：NSUTF8StringEncoding 吗？

【解决方案2】：

您的代码在我的最后工作，我刚刚测试过它。你在哪里检查你的变化？使用 Documents 目录路径。获取路径 -

NSLog(@"%@",documentsDirectory);

从控制台复制路径，然后打开查找器，按 Cmd+shift+g 并在此处粘贴路径，然后打开您的文件

【讨论】：

我想这是我错的地方。我在我的资源应用程序目录中创建了 MyFile。但那里没有更改。我在哪里检查或创建文件？跨度>

【解决方案3】：

斯威夫特

func saveFile() {
    let paths = NSSearchPathForDirectoriesInDomains(.DocumentDirectory, .UserDomainMask, true)
    let documentsDirectory = paths[0] as! String
    let fileName = "\(documentsDirectory)/textFile.txt"
    let content = "Hello World"
    content.writeToFile(fileName, atomically: false, encoding: NSUTF8StringEncoding, error: nil)
}

func loadFile() {
    let paths = NSSearchPathForDirectoriesInDomains(.DocumentDirectory, .UserDomainMask, true)
    let documentsDirectory = paths[0] as! String
    let fileName = "\(documentsDirectory)/textFile.txt"
    let content: String = String(contentsOfFile: fileName, encoding: NSUTF8StringEncoding, error: nil)!
    println(content)
}

斯威夫特 2

func saveFile() {
    let paths = NSSearchPathForDirectoriesInDomains(.DocumentDirectory, .UserDomainMask, true)
    let documentsDirectory = paths[0]
    let fileName = "\(documentsDirectory)/textFile.txt"
    let content = "Hello World"
    do{
        try content.writeToFile(fileName, atomically: false, encoding: NSUTF8StringEncoding)
    }catch _ {

    }

}

func loadFile()->String {
    let paths = NSSearchPathForDirectoriesInDomains(.DocumentDirectory, .UserDomainMask, true)
    let documentsDirectory = paths[0] 
    let fileName = "\(documentsDirectory)/textFile.txt"
    let content: String
    do{
       content = try String(contentsOfFile: fileName, encoding: NSUTF8StringEncoding)
    }catch _{
        content=""
    }
    return content;
}

斯威夫特 3

func saveFile() {
    let paths = NSSearchPathForDirectoriesInDomains(.documentDirectory, .userDomainMask, true)
    let documentsDirectory = paths[0]
    let fileName = "\(documentsDirectory)/textFile.txt"
    let content = "Hello World"
    do{
        try content.write(toFile: fileName, atomically: false, encoding: String.Encoding.utf8)
    }catch _ {

    }

}

func loadFile()->String {
    let paths = NSSearchPathForDirectoriesInDomains(.documentDirectory, .userDomainMask, true)
    let documentsDirectory = paths[0]
    let fileName = "\(documentsDirectory)/textFile.txt"
    let content: String
    do{
        content = try String(contentsOfFile: fileName, encoding: String.Encoding.utf8)
    } catch _{
        content=""
    }
    return content;
}

【讨论】：

【解决方案4】：

尝试制作

NSString *appFile = [documentsDirectory stringByAppendingPathComponent:@"MyFile"];

作为

NSString *appFile = [documentsDirectory stringByAppendingPathComponent:@"MyFile.txt"];

【讨论】：