How to Add Pagination in UItableview.

Swift tableView Pagination

For that you need to have server side change also.

1. Server will accept fromIndex and batchSize in the API url as query param.

   let listUrlString =  "http://bla.com/json2.php?listType=" + listType + "&t=" + NSUUID().UUIDString + "&batchSize=" + batchSize + "&fromIndex=" + fromIndex
   

2. In the server response, there will be an extra key totalItems. This will be used to identify all items are received or not. An array or items fromIndex to batchSize number of items.

In the app side

1. First loadItem() will be called with fromIndex = 0 and batchSize = 20 (for example in viewDidLoad() or viewWillAppear). removeAll items from privateList array before calling loadItem() for the first time

2. Server returns an array of first 20 items and totalItems total number of items in the server.

3. Append the 20 items in privateList array and reload tableView

4. In tableView:cellForRowAtIndexPath method check if the cell is the last cell. And check if totalItems (form server) is greater than privateList.count. That means there are more items in the server to load

   if indexPath.row == privateList.count - 1 { // last cell
       if totalItems > privateList.count { // more items to fetch
           loadItem() // increment `fromIndex` by 20 before server call
       }
   }
   

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Question: where is refresh ? will be scrolling ?

Refresh after appending new items in the array when server response received. (step 3)

Scrolling will trigger tableView:cellForRowAtIndexPath for every cell when user scrolls. Code is checking if it is the last cell and fetch remaining items. (step 4)

Sample project added:
https://github.com/rishi420/TableViewPaging

Swift 4 tableView API Pagination

There were many flaws in your logic, so I have rewritten it with minimal changes. Now it will serve your purpose.

import UIKit
struct PagedCharacters: Codable {
    let info: Info
    let results: [Results]

}
struct Info: Codable {
    let count: Int
    let pages: Int
    let next: String
    let prev: String
}

struct Results: Codable {
    let name: String
    let status: String
    let species: String
}

And here is the code for view controller class:

class ViewController: UIViewController, UITableViewDataSource, UITableViewDelegate {

    @IBOutlet var uiTableView: UITableView!
    var aryDownloadedData:[Results]?
    var nextPageUrl:String!

    override func viewDidLoad() {
        super.viewDidLoad()
        getIntitalRickAndMortyData()

        self.uiTableView.dataSource = self
        self.uiTableView.delegate = self

        // Do any additional setup after loading the view.
    }
    func getIntitalRickAndMortyData(){
        aryDownloadedData = []
        //here first page is next page
        nextPageUrl = "https://rickandmortyapi.com/api/character/"
        getRickAndMortyData()
    }

    func getRickAndMortyData() {

        //construct the url, use guard to avoid nonoptional
        guard let urlObj = URL(string: nextPageUrl) else
        { return }

        //fetch data
        URLSession.shared.dataTask(with: urlObj) {[weak self](data, response, error) in

            //to avoid non optional in JSONDecoder
            guard let data = data else { return }

            do {
                //decode object
                let downloadedRickAndMorty = try JSONDecoder().decode(PagedCharacters.self, from: data)
                self?.aryDownloadedData?.append(contentsOf: downloadedRickAndMorty.results)
                self?.nextPageUrl = downloadedRickAndMorty.info.next

                DispatchQueue.main.async {
                    self?.uiTableView.reloadData()
                }
                print(self?.aryDownloadedData as Any)

            } catch {
                print(error)

            }

            }.resume()

    }

    func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        return self.aryDownloadedData?.count ?? 0
    }

    func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {

        if let count = aryDownloadedData?.count, count>1{
            let lastElement = count - 1
            if indexPath.row == lastElement {
                //call get api for next page
                getRickAndMortyData()
            }
        }

        guard let cell = tableView.dequeueReusableCell(withIdentifier: "rickandmortyCell") as? CharacterTableViewCell else { return UITableViewCell() }

        cell.nameLabel.text = "Name: " + (self.aryDownloadedData?[indexPath.row].name ?? "default")

        return cell
    }
}

How to add pagination in UITableView.?

There are many way to achieve this like following way:

• First you need to create one global NSMutableArray that load in TableView Delegates and DataSaurce.
• Now on your api call you need to add That records in global Array.
• On last cell or the tableview you can call it again with next page URL based on your API and reload table on each Call
• You can use for loadMore many thirdParty library available on github:

https://github.com/OpenFibers/DragRefreshAndLoadMoreTableDemo

https://github.com/Abizern/PartialTable

https://github.com/robertmryan/UITableView-Bottom-Refresh

Based On your code:

in .h class

#import <UIKit/UIKit.h>

@interface ViewController : UIViewController
{
   NSURL* nextURL;
    int currentPage;

}

in .M Class

- (void)viewDidLoad {

    currentPage = 1;

    [self LoadData];
    [super viewDidLoad];

}

-(void)LoadData
{

    NSURL *theURL = [NSURL URLWithString:[NSString stringWithFormat:@"http://qa.networc.in:1336/api/dispatcher/rideScheduled/:%d",currentPage]];
    NSMutableURLRequest *theRequest = [NSMutableURLRequest requestWithURL:theURL      cachePolicy:NSURLRequestReloadIgnoringCacheData timeoutInterval:20.0f];

    //Specify method of request(Get or Post)
    [theRequest setHTTPMethod:@"GET"];

    //Pass some default parameter(like content-type etc.)
    [theRequest setValue:@"application/json" forHTTPHeaderField:@"Accept"];
    [theRequest setValue:@"application/json; charset=UTF-8" forHTTPHeaderField:@"Content-Type"];

    [theRequest addValue:token forHTTPHeaderField:@"x-access-token"];
    NSURLResponse *theResponse = NULL;
    NSError *theError = NULL;

    NSData *responseData = [NSURLConnection sendSynchronousRequest:theRequest returningResponse:&theResponse error:&theError];
    if (responseData == nil)
    {
        return;
    }

    NSDictionary *dataDictionaryResponse = [NSJSONSerialization JSONObjectWithData:responseData options:0 error:&theError];
    NSLog(@"url to send request= %@",theURL);
    NSLog(@"%@",dataDictionaryResponse);

    NSURLSession *session = [NSURLSession sharedSession];

    NSURLSessionDataTask *task = [session dataTaskWithRequest:theRequest
                                            completionHandler:
                                  ^(NSData *data, NSURLResponse *response, NSError *error) {

                                      NSLog(@"Response:%@ %@\n", response, error);
                                      if(error == nil)
                                      {

                                          NSString * text = [[NSString alloc] initWithData: data encoding: NSUTF8StringEncoding];
                                          NSLog(@"Data = %@",text);
                                      }

                                      currentPage ++;
                                      dictionary = [[NSJSONSerialization JSONObjectWithData:data options:0 error:nil]objectForKey:@"data"];

                                      NSArray *total =  [dictionary objectForKey:@"total"];
                                      NSLog(@"latlop %@", total);

                                      [getid addObjectsFromArray:total];

                                       [self updateTable];

                                  }];

    [task resume];
}

Infinite scrolling pagination of the TableView

You can see that you have reached the bottom of the list with willDisplay function from the UITableViewDelegate protocol. like below code:

public func tableView(_ tableView: UITableView, willDisplay cell: UITableViewCell, forItemAt indexPath: IndexPath) {
        let lastIndex = self.popularMoviesArray.count - 1
        if indexPath.row == lastIndex {
            // api call and get next page
        }
    }

and you can call API to get the next page data.
then append new data to your data source list and reload tableView:

self.popularMoviesArray.append(contentsOf: newListData)
self.tableView.reloadData()

UITableView Pagination - Bottom Refresh to Load New Data in Swift

Nope, you can't go with that approach because cellForRowAtIndexPath is called many times and also it will take much time to check your conditions!

Here, I have found a better option for UITableView pagination.

func scrollViewDidEndDragging(scrollView: UIScrollView, willDecelerate decelerate: Bool) {

    //Bottom Refresh

    if scrollView == tableView{

        if ((scrollView.contentOffset.y + scrollView.frame.size.height) >= scrollView.contentSize.height)
        {
            if !isNewDataLoading{

                if helperInstance.isConnectedToNetwork(){

                    isNewDataLoading = true
                    getNewData()
                }
            }
        }
    }
}

isNewDataLoading is Bool to check that UITableView is loading new data or not!

Hope this helps!

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