Pass information to UIAlertView delegate - ios

Question

I'm trying to delete a row in table view after confirmation from the user, using an alert view. However I don't know how to let the UIAlertViewDelegate method know which row in the table to delete.
// Override to support editing the table view.
- (void)tableView:(UITableView *)tableView commitEditingStyle:(UITableViewCellEditingStyle)editingStyle forRowAtIndexPath:(NSIndexPath *)indexPath
{
if (editingStyle == UITableViewCellEditingStyleDelete) {
UIAlertView *alert_delete = [[UIAlertView alloc]initWithTitle:[NSString stringWithFormat:#"Confirm Delete %#",[names objectAtIndex:indexPath.row] ] message:#"Warning all student data will be earsed" delegate:self cancelButtonTitle:#"Dismess" otherButtonTitles:#"YES", nil];
[alert_delete show];
// Delete the row from the data source
[tableView deleteRowsAtIndexPaths:#[indexPath] withRowAnimation:UITableViewRowAnimationFade];
} else if (editingStyle == UITableViewCellEditingStyleInsert) {
// Create a new instance of the appropriate class, insert it into the array, and add a new row to the table view
}
}
in alert method i try handle it to delete row from table and database
-(void) alertView:(UIAlertView *)alertView clickedButtonAtIndex:(NSInteger)buttonIndex{
NSString*title = [alertView buttonTitleAtIndex:buttonIndex];
if ([title isEqualToString:#"YES"]) {
// how to pass indexPath.row to alertview
[names removeObjectAtIndex:indexPath.row];
}
}

Answer 1

If you want to pass something to the delegate then add a property to the delegate class and pass the information to it before invoking the alert view:
#interface AlertDelegate : NSObject <UIAlertViewDelegate>
#property (nonatomic) NSIndexPath *indexPath;
#end
// #implementation AlertDelegate omitted
And use thus:
UIAlertView *alertView = ...;
AlertDelegate *delegate = [AlertDelegate new];
alertView.delegate = delegate;
delegate.indexPath = indexPathFromSomewhere;
[alertView show]; // or whatever
If the delegate is self, then that means adding the property to self (or use a private instance variable).
In the delegate method you then have access to the indexPath:
-(void) alertView:(UIAlertView *)alertView clickedButtonAtIndex:(NSInteger)buttonIndex{
NSString*title = [alertView buttonTitleAtIndex:buttonIndex];
if ([title isEqualToString:#"YES"]) {
[names removeObjectAtIndex:self.indexPath.row];
}
}

Answer 2

Add a variable to your tableView controller class to hold the indexPath.row and then use it in the alertview. Save indexPath.row in it before showing the alert.
Also you need to call
[tableView deleteRowsAtIndexPaths:#[indexPath] withRowAnimation:UITableViewRowAnimationFade];
after confirming that user selected YES in the alertView delegate method.

Answer 3

You can also use objc_setAssociatedObject if info to be passed is a collection object. link -
How do you pass a variable to the UIAlertView delegate?

Answer 4

Instead UIAlertview use
CustomAlertview CustomAlertView *lAlert = [[CustomAlertView alloc] init.....
#import <UIKit/UIKit.h>
#interface CustomAlertView : UIAlertView
#property (nonatomic,retain)NSString *mIndex;
#end
#import "CustomAlertView.h"
#implementation CustomAlertView
- (id)initWithFrame:(CGRect)frame
{
self = [super initWithFrame:frame];
if (self) {
// Initialization code
}
return self;
}
/*
// Only override drawRect: if you perform custom drawing.
// An empty implementation adversely affects performance during animation.
- (void)drawRect:(CGRect)rect
{
// Drawing code
}
*/
#end
In the delegate method get the selected data or index as below
- (void)alertView:(UIAlertView *)alertView clickedButtonAtIndex:(NSInteger)buttonIndex {
NSLog(#"index %#",((CustomAlertView *)alertView).mIndex);
}
In the table delegate method assing the index or data as below
- (void)tableView:(UITableView *)tableView commitEditingStyle:(UITableViewCellEditingStyle)editingStyle forRowAtIndexPath:(NSIndexPath *)indexPath{
CustomAlertView *lAlert = [[CustomAlertView alloc] .....
lAlert.mIndex = #"1";
[lAlert show];
lAlert = nil;
}