Credential editing in Plist if Correct - iphone

Question

In plist I have stored Credentials from that I need to check for the correct Credential and if the correct Credential match then replace the password field with the new..for this I Have 3 UITextField . A for new email-id ,b for current password and c for new password ..if a==b means current password == email id then new password entered in the c textfield should replace in the current password field in plist
.
- (void)authenticateCredentials {
NSMutableArray *plistArray = [NSMutableArray arrayWithArray:[self readFromPlist]];
for (int i = 0; i< [plistArray count]; i++)
{
id object = [plistArray objectAtIndex:i];
if ([object isKindOfClass:[NSDictionary class]]) {
NSDictionary *objDict = (NSDictionary *)object;
if ([[objDict objectForKey:#"pass"] isEqualToString:emailTextFeild.text] && [[objDict objectForKey:#"title"] isEqualToString:passwordTextFeild.text])
{
NSLog(#"Correct credentials");
// what should be the condition to replace current password to new password
}
NSLog(#"INCorrect credentials");
} else {
NSLog(#"Error! Not a dictionary");
}
}
}

Answer 1

Check if this will work for you.
- (void)authenticateCredentials {
NSArray *documentPaths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory,
NSUserDomainMask, YES);
NSString *documentsDirectory = [documentPaths objectAtIndex:0];
NSString *documentPlistPath = [documentsDirectory stringByAppendingPathComponent:#"XYZ.plist"];
NSDictionary *dict = [NSDictionary dictionaryWithContentsOfFile:documentPlistPath];
NSArray *plistArray = [dict objectForKey:#"title"];
NSMutableArray *plistUpdatedArray = [NSMutableArray arrayWithArray:plistArray];
for (int i = 0; i< [plistArray count]; i++)
{
id object = [plistArray objectAtIndex:i];
if ([object isKindOfClass:[NSDictionary class]]) {
NSDictionary *objDict = (NSDictionary *)object;
if ([[objDict objectForKey:#"pass"] isEqualToString:emailTextFeild.text] && [[objDict objectForKey:#"title"] isEqualToString:passwordTextFeild.text])
{
NSLog(#"Correct credentials");
NSMutableDictionary *dict1 = [NSMutableDictionary dictionaryWithDictionary:objDict];
[dict1 setObject:newPassword forKey:#"title"];
[plistUpdatedArray replaceObjectAtIndex:i withObject:dict1];
NSMutableDictionary *dict2 = [NSMutableDictionary dictionaryWithDictionary:dict];
[dict2 setObject:plistUpdatedArray forKey:#"title"];
[dict2 writeToFile:documentPlistPath atomically:YES];
return;
}
NSLog(#"INCorrect credentials");
} else {
NSLog(#"Error! Not a dictionary");
}
}
}

Answer 2

If your plist is in bundle you can't change the value stored in it.
So copy it to document directory before doing any change.
Answer to your question:
if([emailField.text isEqualToString:currntPwd.txt])
{
NSMutableDictionary *newDict = [[NSMutableDictionary alloc] init];
[newDict addEntriesFromDictionary:objDict];
[newDict setObject:#"Midhun" forKey:#"pass"];
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory,
NSUserDomainMask, YES);
NSString *docDirectory = [paths objectAtIndex:0];
NSString *plistPath = [docDirectory stringByAppendingPathComponent:#"yourPlist.plist"];
[[NSFileManager defaultManager] removeItemAtPath:plistPath];
[newDict writeToFile:plistPath atomically:YES];
}