iOS UITableView numberOfRowsInSection错误访问

Question

I'm calling the numberOfRowsInSection method of the UITableView delegate inside of the heightForRowAtIndexPath but it gives me a Bad Access Error :

- (CGFloat) tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath{
    ...
    NSLog(@"number of rows in section: %i", [tableView numberOfRowsInSection:[indexPath section]]);
    ...
}

Can anybody tell me whats wrong here?

Answer 1

You are calling an delegate method.

When you call this method, it'll invoke the related delegates method like cellForRowAtIndexPath , heightForRowAtIndexPath etc.

It'll cause an infinite loop that's why it's crashing.

Answer 2

That's normal.. In that moment your UITableView is being created. You shouldn't call methods related to your UITableView , before it has been build. You should rely in other mechanism to get the height of your Cells.

Answer 3

You need to return an actual value here. So instead of calling [tableView numberOfRowsInSection:[indexPath section]] simply do the same thing again.

In order not to duplicate your code you could create a helper method which you can call in both places, namely, your heightForRowAtIndexPath method and the numberOfRowsInSection method:

- (int) myNumberOfRowsMethod{
    // Here you would usually have some underlying model 
    return [self.myContactsOrWhateverArray count];
}

Answer 4

You are calling

[tableView numberOfRowsInSection:section];

You should be calling

[self numberOfRowsInSection:section];