self.tableView reloadData doesn't work in UISplitViewController master detail application - ios

Question

I was trying to update tableview in masterviewcontroller from detailviewcontroller using delegate. I called reloadData from delegate methods but it didn't wwork. I still couldn't solve this.
this is my delegate method in MasterViewController
- (void)updateScore:(DetailViewController *)controller withScore:(NSUInteger)score {
UITableViewCell *cell = [self.tableView cellForRowAtIndexPath:_selectedIndexPath];
NSLog(#"%#", cell.detailTextLabel.text);
cell.detailTextLabel.text = [NSString stringWithFormat:#"Best score: %lu", (unsigned long)score];
[self.tableView reloadData];
NSLog(#"%#", cell.detailTextLabel.text);
}
from NSLog the cell.detailTextLabel.text was updated, but the tableview doesn't reload
thanks

Answer 1

You need to make sure that your view controller is the tableview delegate and the datasource
If you are using storyboards, under connections inspector, your tableview needs your view controller set as dataSource and delegate
if you want to just do it in your viewcontroller.m file in the viewDidLoad method you can use these lines
self.tableView.delegate = self;
self.tableView.dataSource = self;

Answer 2

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
static NSString *CellIdentifier = #"Cell";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if (cell == nil) {
cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier];
//other init
}
if(_selectedIndexPath.row == indexPath.row && _selectedIndexPath.section == indexPath.section){
cell.detailTextLabel.text = [NSString stringWithFormat:#"Best score: %lu", (unsigned long)score];
}
}
Your can try move code in cellForRowAtIndexPath above then tableView reloadData

Answer 3

[self.tableView reloadData] updates all visible cells in the table. It calls numberOfSectionsInTableView, numberOfRowsInSection, cellForRowAtIndexPath and so on. In other words: It completely renews the table.
The only correct way to set cell content is to set it in cellForRowAtIndexPath. The code:
if (cell == nil) { cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier]; //other init}
never gets called since iOS 6 if you use storyboards.
So with your code you:
use an incorrect way to setup cell content.
clear all your settings with [self.tableView reloadData].
Solution:
Save score in __strong ivar or property.
Call [self.tableView reloadData]. It calls cellForRowAtIndexPath at appropriate times.
Setup a new score in cellForRowAtIndexPath method.
Suggestion: Use:
dispatch_async(dispatch_get_main_queue(), ^(){ [self.tableView reloadData]; });
to return fast from the delegate and not wait until the table was updated.