objective-c - 将 NSString 写入文件

Question

我正在尝试将字符串写入文件并将其存储在我的应用程序的 applicationSupport 文件夹中。但是我的 NSLog() 语句没有在调试器中记录任何内容。我试图用调试器检查它，我可以看到内容是 nil，所以我猜这就是它不输出任何东西的原因，但我不知道为什么它设置为 nil。谁能看到我的错误？

 NSString *document = [[[[[[[[description stringByAppendingString:@" "]stringByAppendingString:focus]stringByAppendingString:@" "]stringByAppendingString:level]stringByAppendingString:@" "]stringByAppendingString:equipment]stringByAppendingString:@" "]stringByAppendingString:waterDepth];
//NSLog(@"%@", document);

//get the documents directory:
NSArray *paths = NSSearchPathForDirectoriesInDomains
(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *supportDirectory = [paths objectAtIndex:0];

//filename
NSString *filename = [NSString stringWithFormat:[_nameTextField.text stringByAppendingString:@".txt"], supportDirectory];

[document writeToFile:filename atomically:NO encoding:NSStringEncodingConversionAllowLossy error:nil];

NSString *content = [[NSString alloc]initWithContentsOfFile:filename usedEncoding:nil error:nil];
NSLog(@"%@", content);

Answer 1

filename是错的。它应具有以下格式："directory/file.extension". 您可以使用方法stringByAppendingPathComponent和stringByAppendingPathExtension构造这样的字符串。

NSString *filename = [supportDirectory stringByAppendingPathComponent:[_nameTextField.text stringByAppendingPathExtension:@"txt"]];

---

另外，作为旁注，第一行应该这样重写stringWithFormat：

NSString *document = [NSString stringWithFormat:@"%@ %@ %@ %@ %@", description, focus, level, equipment, waterDepth];

Answer 2

你有错误的初始化文件名​​。它应该是：

  NSString *filename = [NSString stringWithFormat:@"%@/%@", supportDirectory,[_nameTextField.text stringByAppendingString:@".txt"]];

它会起作用的！祝你好运：）

Answer 3

这

NSString *filename = [NSString stringWithFormat:[_nameTextField.text stringByAppendingString:@".txt"], supportDirectory];

是错的。它应该是：

NSString *filename = [NSString stringWithFormat:"%@%@",[_nameTextField.text stringByAppendingString:@".txt"], supportDirectory];