UItableView load data on scroll in ios - ios

Question

Hi in my array there is huge amount of data and I have to display it in UITableView. But the condition here is I have to display only 5 records initially,then once the user scroll down I have to load more records.I tried searching it but didn't get any useful answer please help me and I agree that we have to use ((void)tableView:(UITableView *)tableView willDisplayCell:(UITableViewCell *)cell forRowAtIndexPath:(NSIndexPath *)indexPath )
Another way
we can adjust the return value of tableView:numberOfRowsInSection: method, every time we want to insert ten rows, you can plus 5 to the return value.
but i am not understand how to do this please help me
my code:
#import "TableViewController.h"
#interface TableViewController ()
{
UITableView * tableView;
NSUInteger reloads_;
NSMutableArray * MainArray;
int scrollValue;
long dataLimit;
NSArray * yourDataSource;
}
#end
#implementation TableViewController
- (void)viewDidLoad
{
[super viewDidLoad];
MainArray = [[NSMutableArray alloc]initWithObjects:#"1",#"2",#"3",#"4",#"5",#"6",#"7",#"8",#"9",#"10",nil];
tableView = [[UITableView alloc] initWithFrame:self.view.bounds style:UITableViewStylePlain];
tableView.delegate = self;
tableView.dataSource = self;
tableView.backgroundColor = [UIColor clearColor];
[self.view addSubview:tableView];
}
#pragma mark - UITableViewDataSource
// number of section(s), now I assume there is only 1 section
- (NSInteger)numberOfSectionsInTableView:(UITableView *)theTableView
{
return 1;
}
// number of row in the section, I assume there is only 1 row
- (NSInteger)tableView:(UITableView *)theTableView numberOfRowsInSection:(NSInteger)section
{
return yourDataSource.count;
}
// the cell will be returned to the tableView
- (UITableViewCell *)tableView:(UITableView *)theTableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
static NSString *CellIdentifier = #"newFriendCell";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if (cell == nil) {
cell = [[UITableViewCell alloc]initWithStyle:UITableViewCellStyleSubtitle reuseIdentifier:CellIdentifier];
}
cell.textLabel.text = [yourDataSource objectAtIndex:indexPath.row];
return cell;
}
- (void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView{
[self estimatedTotalData];
}
- (void)estimatedTotalData
{
long currentRow = ((NSIndexPath *)[[tableView indexPathsForVisibleRows] lastObject]).row;
// 25 here is the initial data count
long estimateDataCount = 25;
while (currentRow > estimateDataCount)
{
estimateDataCount+=25;
}
dataLimit = estimateDataCount;
if (dataLimit == currentRow+1)
{
dataLimit+=25;
if (dataLimit != estimateDataCount)
{
//[self requestForData]; or load necessary data
// take not that dataLimit is the total data that must be displayed.
NSArray *yourLocalData = #[#"1", #"2", #"3", #"4", #"5"];
// just add more sample objects
yourDataSource = [self setsLimitForObject: yourLocalData limit: dataLimit];
[tableView reloadData];
}
}
}
- (NSArray *)setsLimitForObject:(id)object limit:(long)limit
{
if ([object isKindOfClass:[NSArray class]])
{
NSMutableArray *tempArray = [object mutableCopy];
NSRange range = NSMakeRange(0, limit);
if (tempArray.count >= range.length)
return [tempArray subarrayWithRange:range];
else
{
NSLog(#"Out of bounds");
return object;
}
} else NSLog(#"Sets Log: Cannot set limit for object %#", [object class]);
return nil;
}
#end

Answer 1

Try this approach, this is more like a paging...
- (void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView
{
[self estimatedTotalData];
}
- (void)estimatedTotalData
{
long currentRow = ((NSIndexPath *)[[YourTableView indexPathsForVisibleRows] lastObject]).row;
// 25 here is the initial data count
long estimateDataCount = 25;
while (currentRow > estimateDataCount)
{
estimateDataCount+=25;
}
dataLimit = estimateDataCount;
if (dataLimit == currentRow+1)
{
dataLimit+=25;
if (dataLimit != estimateDataCount)
{
//[self requestForData]; or load necessary data
// take not that dataLimit is the total data that must be displayed.
NSArray *yourLocalData = #[#"1", #"2", #"3", #"4", #"5"];
// just add more sample objects
yourDataSource = [self setsLimitForObject: yourLocalData limit: dataLimit];
[yourTable reloadData];
}
}
}
Update:
- (NSArray *)setsLimitForObject:(id)object limit:(long)limit
{
if ([object isKindOfClass:[NSArray class]])
{
NSMutableArray *tempArray = [object mutableCopy];
NSRange range = NSMakeRange(0, limit);
if (tempArray.count >= range.length)
return [tempArray subarrayWithRange:range];
else
{
NSLog(#"Out of bounds");
return object;
}
} else NSLog(#"Sets Log: Cannot set limit for object %#", [object class]);
return nil;
}

Answer 2

You can use below code for your cellForRowAtIndexPath,
- (UITableViewCell *)tableView:(UITableView *)theTableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
static NSString *CellIdentifier = #"newFriendCell";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if (cell == nil) {
cell = [[UITableViewCell alloc]initWithStyle:UITableViewCellStyleSubtitle reuseIdentifier:CellIdentifier];
}
cell.textLabel.text = [mainArray objectAtIndex:indexPath.row];
if (indexPath.row % 5 == 0) { // this if loop will get execute at every fifth row
// if you are loading data from API response then call API here and add next set of data into your existing array.
// then just reload your tableview by it's name e.g. [theTableView reloadData];
}
return cell;
}
and for your numberOfRowsInSection, instead of fixed 5 rows, just use mainArray.count like below,
- (NSInteger)tableView:(UITableView *)theTableView numberOfRowsInSection:(NSInteger)section
{
return mainArray.count;
}