How to add string and key to dictionary in iPhone programmatically? - iphone

Question

I used the following code to write values to dictionary, but when add new one to the dictionary it is not updating, it just displays the plist with only recently added value and it is crashing too.
nameString=nameTxt.text;
NSFileManager *mngr=[NSFileManager defaultManager];
NSArray *docDir=NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *docPath=[docDir objectAtIndex:0];
NSString *filePath=[docPath stringByAppendingPathComponent:#"score.plist"];
NSString *bundlePath=[[NSBundle mainBundle] pathForResource:#"score" ofType:#"plist"];
if ([mngr fileExistsAtPath:filePath]) {
NSLog(#"File exists");
}
else {
NSLog(#"NO file exists");
[[NSFileManager defaultManager] copyItemAtPath:bundlePath toPath:filePath error:NULL];
}
dict=[[NSMutableDictionary alloc]init];
dict=[NSMutableDictionary dictionaryWithContentsOfFile:filePath];
NSLog(#"dict is %#",dict);
[dict setObject:nameString forKey:#"100"];
[dict writeToFile:filePath atomically:YES];
[dict release];
I get crash when I used the last line "[dict release]"
I have a score.plist file in my bundle.

Answer 1

The crash is due to this line,
dict=[[NSMutableDictionary alloc]init];
dict=[NSMutableDictionary dictionaryWithContentsOfFile:filePath];
first line you are allocting memory and then you are overwriting the dict param to link to static dictionary which is not owned by you. So the old one is leaked and when you are releasing it tries to release the static one.
Instead of that use,
dict=[NSMutableDictionary dictionaryWithContentsOfFile:filePath];
and do NOT use release statement. Since you dont own it, you dont have to release it.
Check this

Answer 2

This is a simple memory problem.Along with solving the problem you have to understand the problem.
The dict is a NSMutableDictionary that you declared globally. And so that you can alloc it for using this so that you won't lose the scope of the dictionary.
So in the beginning say 'ViewDidLoad:' , you can alloc and init this as
dict=[[NSMutableDictionary alloc]init];
or in the present condition you can use like
dict=[[NSMutableDictionary alloc]initWithContentsOfFile: filePath];
So that you can alloc the dictionary with the score.plist file and everything will work fine.
What happended in your case is you alloced the dict. But in the next line you replace the alloced object of dict with autoreleaed object by the statement
dict=[NSMutableDictionary dictionaryWithContentsOfFile:filePath];
As the class methods always returns autoreleased objects, when you try to release the object which is autoreleased, it crashes. :-)
Hope you got the idea.
Now the solution is you can change the line
dict=[[NSMutableDictionary alloc]init];
To
dict=[[NSMutableDictionary alloc]initWithContentsOfFile: filePath];
And remove the line
dict=[NSMutableDictionary dictionaryWithContentsOfFile:filePath];
Everything will work. Happy Coding. :-)