未从文件中检索内容
我遇到了这个有线问题，我无法从文件中获取内容并用它启动我的 NSMutableArray。
这是我的代码：
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDirectory = [paths objectAtIndex:0];
NSLog(@"Does file exist?: %i", [[NSFileManager defaultManager] fileExistsAtPath:[NSString stringWithFormat: @"%@/length.txt", documentsDirectory]]);
NSMutableArray *tempArr;
tempArr = [[NSMutableArray alloc] initWithContentsOfFile:[NSString stringWithFormat: @"%@/length.txt", documentsDirectory]];
尝试此操作时，initWithContentsOfFile 返回（null）。检查文件是否存在的行将“1”打印到控制台。
这是我用来保存数据的代码：
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDirectory = [paths objectAtIndex:0];
[length.text writeToFile:[NSString stringWithFormat: @"%@/length.txt", documentsDirectory] atomically:NO];
我在不同的程序中使用或多或少完全相同的代码，没有任何问题。
这里真的需要一些帮助，也许我现在只是盲目的......
I've got this wired problem, I cannot get the content from the file and initiate my NSMutableArray with it.
Here's my code:
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDirectory = [paths objectAtIndex:0];
NSLog(@"Does file exist?: %i", [[NSFileManager defaultManager] fileExistsAtPath:[NSString stringWithFormat: @"%@/length.txt", documentsDirectory]]);
NSMutableArray *tempArr;
tempArr = [[NSMutableArray alloc] initWithContentsOfFile:[NSString stringWithFormat: @"%@/length.txt", documentsDirectory]];
When trying this, initWithContentsOfFile returns (null). The row checking if the file exist prints '1' to the console.
This is the code I'm using to save the data:
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDirectory = [paths objectAtIndex:0];
[length.text writeToFile:[NSString stringWithFormat: @"%@/length.txt", documentsDirectory] atomically:NO];
I'm using more or less exactly the same code in a different program without problems.
Really need some help here, perhaps I'm just blind for the moment...
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当您尝试从文件内容创建数组时， 文件必须采用plist格式，并且最外层的plist元素必须是
< ;数组>。如果它不具有该格式，初始化将失败并且您的数组将为nil。您通过将
NSString写入文件来创建文件，这意味着您可能应该将其读入NSString，而不是NSArray>。When you try to create an array from the contents of a file, the file must be in plist format, and the outer-most plist element must be
<array>. If it doesn't have that format, initialization will fail and your array will benil.You're creating the file by writing an
NSStringto a file, which means you should probably be reading it in to anNSString, not anNSArray.NSArray 的
initWithContentsOfFile:方法的文档说：您的代码片段中没有包含
length的声明，但我猜测length.text返回一个 NSString 对象，而不是 NSArray。因此，您需要使用 NSString（而不是 NSArray）中的initWithContentsOfFile:从文件中读回该内容。The docs for NSArray's
initWithContentsOfFile:method say:You don't include the declaration of
lengthin your code snippet, but I'm guessing thatlength.textreturns an NSString object, not an NSArray. So you'd need to read that back from a file usinginitWithContentsOfFile:from NSString, not NSArray.