string = textView.text, yet string is (nul) - ios

Question

I've literally tried everything. I'm sure my mistake is going to be something as stupid and small as a missed self.string, but I can't seem to get it working. What my mini program does is checks if a file named Code.txt already exists. If it does exist, then it will load the file in a UITextView (and it does this just fine). If it doesn't exist, it will create a file name Code.txt. All of this works just fine.
However, when I try to save the current text inside the UITextView to the file, I am unable to save it to the string first. This is what I am trying to achieve:
Upon exiting the app: textView.text --> codeString --> Code.txt [saved]
Except, again, I am unable to save the textView.text to the string (codeString). The NSLog is returning it as a nut (see NSLog(#"String: %#", self.codeString); in the saveFile method).
ViewController.h
#import <UIKit/UIKit.h>
#import "AppDelegate.h"
#import "BuildViewController.h"
#interface ViewController : UIViewController <UITextViewDelegate>
#property (nonatomic, strong) NSString *codeString;
#property (nonatomic, retain) IBOutlet UITextView *textView;
#property (nonatomic, retain) BuildViewController *buildViewController;
- (void)saveFile;
#end
ViewController.m
#import "ViewController.h"
#interface ViewController ()
#end
#implementation ViewController
#synthesize textView;
- (void)viewDidLoad {
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
textView.delegate = self;
// Check if Code.txt exists
NSString* documentsDir = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) objectAtIndex:0];
NSString *codeFile = [NSString stringWithFormat:#"%#/Code.txt", documentsDir];
BOOL fileExists = [[NSFileManager defaultManager] fileExistsAtPath:codeFile];
NSLog(#"viewWillAppear");
if (fileExists == true) {
// Code.txt does exist, continue to viewDidLoad
NSLog(#"Code.txt does exist");
}
else if (fileExists == false) {
// Code.txt does not exist, create the file
NSLog(#"Code.txt does not exist");
ViewController *viewController = [ViewController alloc];
[viewController createFile];
}
self.textView.delegate = self;
}
- (void)viewWillAppear:(BOOL)animated {
// Load Code.txt
NSString* documentsDir = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) objectAtIndex:0];
NSString* codeFile = [documentsDir stringByAppendingPathComponent:#"Code.txt"];
NSString *codeString = [NSString stringWithContentsOfFile:codeFile encoding:NSUTF8StringEncoding error:NULL];
textView.text = codeString;
NSLog(#"Loaded Code.txt");
}
- (void)saveFile {
// Save text to Code.txt
self.codeString = textView.text;
NSString *documentsDir = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) objectAtIndex:0];
NSString *codeFile = [NSString stringWithFormat:#"%#/Code.txt", documentsDir];
[self.codeString writeToFile:codeFile
atomically:NO
encoding:NSStringEncodingConversionAllowLossy
error:nil];
NSLog(#"String: %#", self.codeString);
NSLog(#"Saved text to Code.txt");
}
- (void)createFile {
NSString *documentsDir = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) objectAtIndex:0];
NSString *codeFile = [NSString stringWithFormat:#"%#/Code.txt", documentsDir];
NSString *codeString = #"print(\"Hello, world\")";
[codeString writeToFile:codeFile
atomically:NO
encoding:NSStringEncodingConversionAllowLossy
error:nil];
NSLog(#"Created Code.txt");
}
- (void)didReceiveMemoryWarning {
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
#end

Answer 1

Your error is you create a new instance of ViewController like #Avi said.
You should get the existing instance in memory
If you want to save file when in background,you may register notification
In viewDidLoad,add this line
[[NSNotificationCenter defaultCenter] addObserver:self selector:#selector(enterBackground:) name:UIApplicationDidEnterBackgroundNotification object:nil];
Then add this function to ViewController
-(void)enterBackground:(NSNotification *)notification{
[self saveFile];
}
Then in dealloc
-(void)dealloc{
[[NSNotificationCenter defaultCenter] removeObserver:self name:UIApplicationDidEnterBackgroundNotification object:nil];
}