iphone - How Can i get data from the file in the documents folder

Question

i am new to xcode and objective c.

firstly i have created a file in documents directory and it is created and now what i need is how can i read the data from that file like whether the file is containing a particular string or not

How can i get that

Answer 1

您可以在这里按照我的回答，保存和检索 plist 文件

XCode中文件中的数组

Answer 2

与您编写的方式相同，您可以检索数据，假设您想从文档文件夹中获取图像，然后查看此代码 -

NSString *stringPath = [[NSSearchPathForDirectoriesInDomains(NSDocumentDirectory,  NSUserDomainMask, YES)objectAtIndex:0]];
NSString *fileName = [stringPath stringByAppendingFormat:@"/image.jpg"];

//fileName is your image path and image.jpg is your image name which is saved in documents folder...
NSData *retrieveData = [NSData dataWithContentsOfFile:fileName];
UIImage *newImage = [UIImage imageWithData: retrieveData];

在这种情况下，而不是

[data writeToFile:fileName atomically:YES]; 

你必须写

NSData *retrieveData = [NSData dataWithContentsOfFile:fileName];

线。你可以得到所有类型的数据。

谢谢你！！

Answer 3

以下方法将文件的内容获取到一个字符串。

+ (id)stringWithContentsOfFile:(NSString *)path
              usedEncoding:(NSStringEncoding *)enc
                     error:(NSError **)error

然后，您可以通过以下方式确定返回的字符串是否包含指定的子字符串：

NSRange textRange;
textRange =[string rangeOfString:@"ohai"];

if(textRange.location != NSNotFound) {

    //String contains substring "ohai"
}

希望这可以帮助。

Answer 4

您可以通过以下方式从文档文件夹中的文件中读取数据：

 NSString *filePath = [NSHomeDirectory() stringByAppendingPathComponent:@"Documents/<pathofFile>"];
 NSString *fileContent = [[NSString alloc] initWithContentOfFile:filePath encoding:NSUTF8StringEncoding error:nil];

现在，您可以使用 NSString 方法在 fileContent 中搜索子字符串。