Demonstrates the various NSDataWritingOptions. Should be used with a program like iExplorer to see how these file behave. http://www.macroplant.com/iexplorer/

gistfile1.m

[MyClass writeStringWithFileName:@"Complete"
                          option:NSDataWritingFileProtectionComplete];

[MyClass writeStringWithFileName:@"CompleteUnlessOpen"
                          option:NSDataWritingFileProtectionCompleteUnlessOpen];

[MyClass writeStringWithFileName:@"CompleteUntilFirstUserAuthentication"
                          option:NSDataWritingFileProtectionCompleteUntilFirstUserAuthentication];

[MyClass writeStringWithFileName:@"None"
                          option:NSDataWritingFileProtectionNone];

// ...

+ (void) writeStringWithFileName:(NSString *)fileName
                          option:(NSDataWritingOptions)option
{
    NSString * string = @"My sensitive data";
    NSData * data = [string dataUsingEncoding:NSUTF8StringEncoding];
    
    NSString * documentsPath = [NSSearchPathForDirectoriesInDomains(NSLibraryDirectory, NSUserDomainMask, YES) lastObject];
    NSString * path = [[documentsPath stringByAppendingPathComponent:fileName] stringByAppendingPathExtension:@"txt"];
    
    NSError * error = nil;
    
    [data writeToFile:path
              options:option
                error:&error];
    
    NSAssert(!error, @"Error with writeToFile %@", error);
}

    // ....