如何判断 UITableView 是否包含特定的 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;
}

Answer 1

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
}

Answer 2

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)
    }
}

Answer 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)
}

Answer 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.

Answer 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;
}

Answer 6

你也可以使用 UITableView 的numberOfRowsInSection方法。

Answer 7

I iterated upon Kamran's answer :

+ (BOOL)isIndexPath:(NSIndexPath *)indexPath inTableView:(UITableView *)tableView {
    if (!indexPath) {
        return NO;
    }
    if (indexPath.section < [tableView numberOfSections]) {
        if (indexPath.row < [tableView numberOfRowsInSection:indexPath.section]) {
            return YES;
        }
    }
    return NO;
}

Answer 8

You could try to get UITableViewCell by :

- (UITableViewCell *)cellForRowAtIndexPath:(NSIndexPath *)indexPath;
// returns nil if cell is not visible or index path is out of range

here's the complete code :

UITableViewCell *cell = [cellForRowAtIndexPath:appDelegate.currentMainIndexPath];

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