Question

I want to know that difference between following two lines

 name1 = [[NSString stringWithUTF8String:(char *)sqlite3_column_text(compiledStatement,1)] retain];

 name1 = [NSString stringWithUTF8String:(char *)sqlite3_column_text(compiledStatement,1)];

What will be effect on name1 if I do use retain at the last,

I face once problem, and couldn’t use name1 in a method that is being call by NSTimer, and when I use retain, they it worked fine for me.

If I do call value from database in viewDidLoad, and use in a method that is being called by NSTimer after each second, then it will give bad-exec, but when I do use retain then it will work properly,

I want to know the reason

Answer 1

Here is the difference

- (void)func1 {
    name1 = [[NSString stringWithUTF8String:...] retain];
    name2 = [NSString stringWithUTF8String:...];
}

- (void)func2 {
    NSLog(@"%@", name1);    //OK, name1 is still there
    NSLog(@"%@", name2);    //Would be crashed because name2 could be released anytime after func1 is finished.
}