IOS——文件和文件夹管理

Question

我现在正在学习如何在 iOS 中创建和管理文件和文件夹。但我似乎无法正确处理文件夹部分。我下面的代码有什么问题？

- (void)viewDidLoad
{
    [super viewDidLoad];
    NSFileManager *filemgr;
    NSString *dataFile;
    NSString *docsDir;
    NSString *newDir;
    NSArray *dirPaths;
    BOOL isDir;

filemgr = [NSFileManager defaultManager];

// Identify the documents directory
dirPaths = NSSearchPathForDirectoriesInDomains(
                                               NSDocumentDirectory, NSUserDomainMask, YES);

docsDir = dirPaths[0];

// Build the path to the data file
if ([filemgr fileExistsAtPath:@"newfolder" isDirectory:&isDir] && isDir) {
    NSLog(@"folder already created!");
}else{
    NSLog(@"create new folder now...");
    newDir = [docsDir stringByAppendingPathComponent:@"newfolder"];
}

dataFile = [docsDir stringByAppendingPathComponent:
            @"/newfolder/datafile.dat"];

// Check if the file already exists
if ([filemgr fileExistsAtPath: dataFile])
{
    // Read file contents and display in textBox
    NSData *databuffer;
    databuffer = [filemgr contentsAtPath: dataFile];

    NSString *datastring = [[NSString alloc]
                            initWithData: databuffer
                            encoding:NSASCIIStringEncoding];

    _textBox.text = datastring;
}

}


- (IBAction)saveText:(id)sender {
    NSFileManager *filemgr;
    NSData *databuffer;
    NSString *dataFile;
    NSString *docsDir;
    NSArray *dirPaths;

    filemgr = [NSFileManager defaultManager];

    dirPaths = NSSearchPathForDirectoriesInDomains(
                                                   NSDocumentDirectory, NSUserDomainMask, YES);

    docsDir = dirPaths[0];
    dataFile = [docsDir
                stringByAppendingPathComponent: @"/newfolder/datafile.dat"];
    databuffer = [_textBox.text
                  dataUsingEncoding: NSASCIIStringEncoding];
    [filemgr createFileAtPath: dataFile
                     contents: databuffer attributes:nil];
}

我不确定会发生什么，但每次我运行模拟时，它都会给我一个空白文本字段，尽管我之前已经输入了一些文本。我遵循了 Here 中的教程并用谷歌搜索目录创建部分的其他示例。好像出了什么问题？？谢谢!

Answer 1

问题出在这一行:

if ([filemgr fileExistsAtPath:@"newfolder" isDirectory:&isDir] && isDir) {
    NSLog(@"folder already created!"); 

You need to pass the complete path as argument of fileExistsAtPath Like:

NSSTring *folderPath = [docsDir stringByAppendingPathComponent:
            @"newfolder"];
if ([filemgr fileExistsAtPath:folderPath isDirectory:&isDir] && isDir) {
        NSLog(@"folder already created!");