How can I tell if a UITableView contains a specific NSIndexPath?

Question

Here is the code I'm using:

if (appDelegate.currentMainIndexPath != nil /* && doesPathExistInTableView */)
{
    [tblView scrollToRowAtIndexPath:appDelegate.currentMainIndexPath atScrollPosition:UITableViewScrollPositionTop animated:NO];
    appDelegate.currentMainIndexPath = nil;
}

Solution 1

A Swift adaptation of Kamran Khan's answer:

extension UITableView {
  func hasRowAtIndexPath(indexPath: NSIndexPath) -> Bool {
    return indexPath.section < self.numberOfSections && indexPath.row < self.numberOfRowsInSection(indexPath.section)
  }
}

Swift 4:

extension UITableView {
    func hasRow(at indexPath: IndexPath) -> Bool {
        return indexPath.section < self.numberOfSections && indexPath.row < self.numberOfRows(inSection: indexPath.section)
    }
}

Solution 2

You can use this. Pass it indexpath's row and section

Objective C:

-(BOOL) isRowPresentInTableView:(int)row withSection:(int)section
{
    if(section < [self.tableView numberOfSections])
    {
        if(row < [self.tableView numberOfRowsInSection:section])
        {
            return YES;
        }
    }
    return NO;
}

Swift 3:

func isRowPresentInTableView(indexPath: IndexPath) -> Bool{
    if indexPath.section < tableView.numberOfSections{
        if indexPath.row < tableView.numberOfRows(inSection: indexPath.section){
            return true
        }
    }

    return false
}

Solution 3

There is a more convenient method to tell if a indexPath is valid:

For Swift 3.0:

open func rectForRow(at indexPath: IndexPath) -> CGRect

For Objective-C

- (CGRect)rectForRowAtIndexPath:(NSIndexPath *)indexPath;

You will get CGRectZero if the indexPath is invalid.

func isIndexPathValid(indexPath: IndexPath) -> Bool {
    return !tableView.rectForRow(at: indexPath).equalTo(CGRect.zero)
}

Solution 4

If you mean, 'is there a cell at index n' then you just have to compare the size of you datasource to n

if (appDelegate.currentMainIndexPath != nil [datasource count] > n)
{
    [tblView scrollToRowAtIndexPath:appDelegate.currentMainIndexPath atScrollPosition:UITableViewScrollPositionTop animated:NO];
    appDelegate.currentMainIndexPath = nil;
}

Where datasource is for instance an NSArray.

Solution 5

This is how you do it:

indexPath.row < [self.tableView numberOfRowsInSection:indexPath.section]

In context:

if (indexPath.row < [self.tableView numberOfRowsInSection:indexPath.section]) {
    [self.tableView scrollToRowAtIndexPath:indexPath
                          atScrollPosition:UITableViewScrollPositionTop
                                  animated:YES];
}

Inserted into your code:

if (appDelegate.currentMainIndexPath != nil &&
    indexPath.row < [tblView numberOfRowsInSection:indexPath.section]) {
    [tblView scrollToRowAtIndexPath:appDelegate.currentMainIndexPath
                   atScrollPosition:UITableViewScrollPositionTop
                           animated:NO];
    appDelegate.currentMainIndexPath = nil;
}

View more solutions

Comments

[Erik B]

Why is this the accepted answer? The code is not even valid Objective-C and even if you fix the compile errors, you'd still be using a method that returns nil if the cell isn't visible, which means that you cannot scroll to something that isn't already on the screen and the whole point of scrolling is to make something that isn't visible visible.

[kpower]

If section is wrong, -numberOfRowsInSection: will return NSNotFound, so you should check it also. Or better check indexPath.section < [self.tableView numberOfSections], because NSNotFound isn't documented.

[Nabeel Ahmed]

Apparently Seems a valid answer

[Shu Zhang]

Use NSUInteger or row >= 0 && section >=0 to filter some false cases.

[Brian]

This really should be the accepted answer for Swift 3+. Thank you for the adaptation.

[ScottyBlades]

The call to numberOfRows(inSection: indexPath.section) is causing a crash: Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[myapp tableView:numberOfRowsInSection:]: unrecognized selector sent to instance 0x7fe052825a00'

[ScottyBlades]

The call to numberOfRows(inSection: indexPath.section) is causing a crash: Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[myapp tableView:numberOfRowsInSection:]: unrecognized selector sent to instance 0x7fe052825a00'