To Segue or to didSelectRowAtIndexPath?

问题:

Below is the code that I am currently running. I have a storyboard setup with a nav controller and tableview controller and a view controller. I am trying to pass the name from the NSDictionary that I have setup for the Table to the detail view controller. Should I use prepareforsegue or didselectrowatindexpath and how would I get the name out of the dictionary to pass it along?

#import "FMInboxViewController.h"
#import "FMDetailViewController.h"

@interface FMInboxViewController ()

@end

@implementation FMInboxViewController

@synthesize keyArray;
@synthesize tableArray;
@synthesize tblDictionary;
@synthesize filteredArray;

- (void)viewDidLoad
{
    [super viewDidLoad];

    NSMutableArray *ary=[[NSMutableArray alloc]init];
    [ary addObject:@"Adam"];
    [ary addObject:@"Fred"];
    [ary addObject:@"Angel"];
    // ... many similar entries
    [ary addObject:@"James"];
    [ary addObject:@"Mukthesh"];

    self.tblDictionary =[self fillingDictionary:ary];
}

Table View Data Source

#pragma mark - Table view data source

- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView
{
    // Return the number of sections.
    return [keyArray count];
}

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
    // Return the number of rows in the section.
    NSArray *ary = [self.tblDictionary valueForKey:[keyArray objectAtIndex:section]];
    return [ary count];
}

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
    static NSString *CellIdentifier = @"Cell";
    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier forIndexPath:indexPath];

    NSString *key = [keyArray objectAtIndex:[indexPath section]];
    NSArray *array = (NSArray *)[self.tblDictionary valueForKey:key];
    NSString *cellTitle = [array objectAtIndex:[indexPath row]];
    cell.textLabel.text = cellTitle;

    // Configure the cell...

    return cell;
}

-(NSString *)tableView:(UITableView *)tableView titleForHeaderInSection:(NSInteger)section {
    NSString *title = [keyArray objectAtIndex:section];
    return title;
}

//-(void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath {
//    NSString *key = [keyArray objectAtIndex:[indexPath section]];
//    NSArray *array = (NSArray *)[self.tblDictionary valueForKey:key];
//    self.selectedName = [array objectAtIndex:indexPath.row];
//    NSLog(@"Selected Name in Did select: %@", self.selectedName);
//    
//    [self performSegueWithIdentifier:@"showDetail" sender:self];
//}

-(void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender {
    if ([segue.identifier isEqualToString:@"showDetail"]) {
        NSIndexPath *section = [self.tableView indexPathForSelectedRow];
        NSString *key = [keyArray objectAtIndex:section];
        NSArray *array = (NSArray *)[self.tblDictionary valueForKey:key];
        NSString *cellTitle = [array objectAtIndex:[indexPath row]];
        NSLog(@"Selected Name in Did select: %@", self.selectedName);
    }
}

Helper methods

#pragma mark - Helper Methods

- (NSMutableDictionary *)fillingDictionary:(NSMutableArray *)sentArray {
    keyArray = [[NSMutableArray alloc] init];
    [keyArray removeAllObjects];
    NSMutableDictionary *dic = [[NSMutableDictionary alloc] init];
    [sentArray sortUsingSelector:@selector(compare:)];
    for ( NSString *str in sentArray) {
        NSString *charVal = [str substringToIndex:1];
        NSString *charStr = [NSString stringWithString:charVal];
        NSLog(@" charStr = %@", charStr);
        if (![keyArray containsObject:charStr]) {
            NSMutableArray *charArray = [[NSMutableArray alloc] init];
            [charArray addObject:str];
            [keyArray addObject:charStr];
            [dic setValue:charArray forKey:charStr];
        }
        else {
            NSMutableArray *prevArray = (NSMutableArray *)[dic valueForKey:charStr];
            [prevArray addObject:str];
            [dic setValue:prevArray forKeyPath:charStr];
        }
    }

    return dic;
}


@end

OK, I changed that section to look like this

-(void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath {
    NSString *key = [keyArray objectAtIndex:[indexPath section]];
    NSArray *array = (NSArray *)[self.tblDictionary valueForKey:key];
    self.selectedName = [array objectAtIndex:indexPath.row];
    NSLog(@"Selected Name in Did select: %@", self.selectedName);
}

-(void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender {
    FMDetailViewController *dvc = (FMDetailViewController *)segue.destinationViewController;
    dvc.name = self.selectedName;
}

However now when I select row the name won't show up in the detail controller on the first press. If you go back and select another name the first name that you pressed then shows up in the view controller. Any suggestions on why this occurs?

回答1:

You need to use both, in didSelectRowAtIndexPath you should call [self performSegueWithIdentifier:@"identifier" sender:self];

In the same View Controller you should have the prepareForSegue method grab the destinationViewController out of the segue, and then set whatever properties on that view controller that you wish to set.

- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
    self.someProperty = [self.someArray objectAtIndex:indexPath.row];
    [self performSegueWithIdentifier:@"segueID" sender:self];
}

- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
{
    UIViewController *vcToPushTo = segue.destinationViewController;
    vcToPushTo.propertyToSet = self.someProperty;
}

回答2:

If possible (and this is the case in almost all standard scenarios), I would use Interface Builder to trigger the segue. You still need to implement prepareForSegue: to configure the destination view controller.

In order to create a segue in IB which triggers a detail view when tapping on a cell or an accessory button (on the right most side of the cell) perform these steps:

1. Control drag from Table View Cell to the destination view controller and release the mouse or trackpad. This opens small selection panel.

2. Choose the source of the trigger, either "Selection segue" or "Accessory action" and the type of the segue ("push", "modal" or "custom").

3. In the Attributes Inspector pane define the "Identifier" of the segue, e.g. "UserShowSegue".

Here's an image from a Demo storyboard in IB which illustrates how the "Table View Cell" in the "Users" view controller is setup to trigger a "push" segue to a detail view controller:

回答3:

Might be an old question, but to be more detailed for whom it may concern:

1- Use both as '(@Peter-Foti)' mentioned.

2- Segue should be linked from the ParentVC to the DestinationVC (NOT from the Prototype Cell).

3- Sender should be set properly.

4- set your '@property (someProperty)'.

SAMPLE CODE:

- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
    self.someProperty = [self.someArray objectAtIndex:indexPath.row];
    [self performSegueWithIdentifier:@"segueID" sender:self.someProperty];
}

- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
{
     UIViewController *vcToPushTo = segue.destinationViewController;
     vcToPushTo.propertyToSet = sender;
}

回答4:

Because didSelectRowAtIndexPath can be replaced with storyboard visual programming, I recommend to do all the logic in the prepareForSegue like this:

override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
    let cell = sender as! UITableViewCell
    let indexPath = tableView.indexPath(for: cell)!
    ... and then use indexPath to set up the destination
}