iosobjective-cuitableviewreloaddata
Performance of UITableView reloadData, reloadSections:withRowAnimation: and reloadRowsAtIndexPaths:withRowAnimation:
I build a test purpose app to test the performance of these three methods on reloading the table view.
//
// ViewController.m
// TableViewSample
//
// Created by Antonio081014 on 8/2/15.
// Copyright (c) 2015 Antonio081014.com. All rights reserved.
//
#import "ViewController.h"
@interface ViewController () <UITableViewDataSource, UITableViewDelegate>
@property (nonatomic, strong) NSArray *listOfCards;
@property (nonatomic, strong) NSIndexPath *selectedIndexPath;
@end
@implementation ViewController
- (void)viewDidLoad {
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
NSMutableArray *list = [NSMutableArray array];
for (int i=0; i<15; i++) {
NSString *carName = [NSString stringWithFormat:@"Car%d", arc4random() % 15];
[list addObject:carName];
}
self.listOfCards = list;
self.tableView.delegate = self;
self.tableView.dataSource = self;
self.selectedIndexPath = nil;
UIBarButtonItem *table = [[UIBarButtonItem alloc] initWithTitle:@"Table" style:UIBarButtonItemStylePlain target:self action:@selector(reloadTable:)];
UIBarButtonItem *section = [[UIBarButtonItem alloc] initWithTitle:@"Section" style:UIBarButtonItemStylePlain target:self action:@selector(reloadSection:)];
UIBarButtonItem *indexPath = [[UIBarButtonItem alloc] initWithTitle:@"IndexPath" style:UIBarButtonItemStylePlain target:self action:@selector(reloadRow:)];
self.navigationItem.rightBarButtonItems = @[table, section, indexPath];
// self.navigationController.navigationItem.rightBarButtonItems = @[table, section, indexPath];
}
- (void)reloadTable:(UIBarButtonItem *)barItem
{
[self.tableView reloadData];
}
- (void)reloadRow:(UIBarButtonItem *)barItem
{
[self reloadRowAtIndexPath:self.selectedIndexPath forBarButtonItem:barItem];
}
- (void)reloadSection:(UIBarButtonItem *)barItem
{
[self reloadSectionAt:0 forBarButtonItem:barItem];
}
- (void)reloadRowAtIndexPath:(NSIndexPath *)indexPath forBarButtonItem:(UIBarButtonItem *)barItem
{
if (indexPath) {
[self.tableView reloadRowsAtIndexPaths:@[indexPath] withRowAnimation:UITableViewRowAnimationAutomatic];
}
}
- (void)reloadSectionAt:(NSUInteger)section forBarButtonItem:(UIBarButtonItem *)barItem
{
[self.tableView reloadSections:[[NSIndexSet alloc] initWithIndex:section] withRowAnimation:UITableViewRowAnimationAutomatic];
}
- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView
{
NSLog(@"Asking Number of Sections in TableView");
return 1;
}
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
NSLog(@"Asking Number of Rows in Section");
return self.listOfCards.count;
}
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:@"Cell" forIndexPath:indexPath];
NSString *carName = self.listOfCards[indexPath.row];
cell.textLabel.text = carName;
return cell;
}
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
self.selectedIndexPath = indexPath;
NSLog(@"Did Select Cell %@", indexPath);
}
- (void)tableView:(UITableView *)tableView didDeselectRowAtIndexPath:(NSIndexPath *)indexPath
{
self.selectedIndexPath = nil;
NSLog(@"Did Deselect Cell %@", indexPath);
}
- (void)tableView:(UITableView *)tableView willDisplayCell:(UITableViewCell *)cell forRowAtIndexPath:(NSIndexPath *)indexPath
{
NSLog(@"Will Display Cell %@", indexPath);
}
- (void)tableView:(UITableView *)tableView didEndDisplayingCell:(UITableViewCell *)cell forRowAtIndexPath:(NSIndexPath *)indexPath
{
NSLog(@"Did End Display Cell %@", indexPath);
}
- (void)tableView:(UITableView *)tableView didHighlightRowAtIndexPath:(NSIndexPath *)indexPath
{
NSLog(@"Did Highlight Cell %@", indexPath);
}
@end
Log when three methods called.
ReloadData
2015-08-03 11:00:51.556 TableViewSample[324:90811] Did End Display Cell {length = 2, path = 0 - 11}
2015-08-03 11:00:51.558 TableViewSample[324:90811] Did End Display Cell {length = 2, path = 0 - 10}
2015-08-03 11:00:51.559 TableViewSample[324:90811] Did End Display Cell {length = 2, path = 0 - 9}
2015-08-03 11:00:51.560 TableViewSample[324:90811] Did End Display Cell {length = 2, path = 0 - 8}
2015-08-03 11:00:51.560 TableViewSample[324:90811] Did End Display Cell {length = 2, path = 0 - 7}
2015-08-03 11:00:51.560 TableViewSample[324:90811] Did End Display Cell {length = 2, path = 0 - 6}
2015-08-03 11:00:51.561 TableViewSample[324:90811] Did End Display Cell {length = 2, path = 0 - 5}
2015-08-03 11:00:51.561 TableViewSample[324:90811] Did End Display Cell {length = 2, path = 0 - 4}
2015-08-03 11:00:51.562 TableViewSample[324:90811] Did End Display Cell {length = 2, path = 0 - 3}
2015-08-03 11:00:51.563 TableViewSample[324:90811] Did End Display Cell {length = 2, path = 0 - 2}
2015-08-03 11:00:51.563 TableViewSample[324:90811] Did End Display Cell {length = 2, path = 0 - 1}
2015-08-03 11:00:51.564 TableViewSample[324:90811] Did End Display Cell {length = 2, path = 0 - 0}
2015-08-03 11:00:51.564 TableViewSample[324:90811] Asking Number of Sections in TableView
2015-08-03 11:00:51.565 TableViewSample[324:90811] Asking Number of Rows in Section
2015-08-03 11:00:51.566 TableViewSample[324:90811] Will Display Cell {length = 2, path = 0 - 0}
2015-08-03 11:00:51.567 TableViewSample[324:90811] Will Display Cell {length = 2, path = 0 - 1}
2015-08-03 11:00:51.567 TableViewSample[324:90811] Will Display Cell {length = 2, path = 0 - 2}
2015-08-03 11:00:51.568 TableViewSample[324:90811] Will Display Cell {length = 2, path = 0 - 3}
2015-08-03 11:00:51.569 TableViewSample[324:90811] Will Display Cell {length = 2, path = 0 - 4}
2015-08-03 11:00:51.569 TableViewSample[324:90811] Will Display Cell {length = 2, path = 0 - 5}
2015-08-03 11:00:51.570 TableViewSample[324:90811] Will Display Cell {length = 2, path = 0 - 6}
2015-08-03 11:00:51.571 TableViewSample[324:90811] Will Display Cell {length = 2, path = 0 - 7}
2015-08-03 11:00:51.572 TableViewSample[324:90811] Will Display Cell {length = 2, path = 0 - 8}
2015-08-03 11:00:51.573 TableViewSample[324:90811] Will Display Cell {length = 2, path = 0 - 9}
2015-08-03 11:00:51.573 TableViewSample[324:90811] Will Display Cell {length = 2, path = 0 - 10}
2015-08-03 11:00:51.574 TableViewSample[324:90811] Will Display Cell {length = 2, path = 0 - 11}
ReloadSection
2015-08-03 11:02:21.641 TableViewSample[324:90811] Asking Number of Sections in TableView
2015-08-03 11:02:21.642 TableViewSample[324:90811] Asking Number of Sections in TableView
2015-08-03 11:02:21.643 TableViewSample[324:90811] Asking Number of Rows in Section
2015-08-03 11:02:21.647 TableViewSample[324:90811] Will Display Cell {length = 2, path = 0 - 0}
2015-08-03 11:02:21.649 TableViewSample[324:90811] Will Display Cell {length = 2, path = 0 - 1}
2015-08-03 11:02:21.651 TableViewSample[324:90811] Will Display Cell {length = 2, path = 0 - 2}
2015-08-03 11:02:21.653 TableViewSample[324:90811] Will Display Cell {length = 2, path = 0 - 3}
2015-08-03 11:02:21.655 TableViewSample[324:90811] Will Display Cell {length = 2, path = 0 - 4}
2015-08-03 11:02:21.657 TableViewSample[324:90811] Will Display Cell {length = 2, path = 0 - 5}
2015-08-03 11:02:21.659 TableViewSample[324:90811] Will Display Cell {length = 2, path = 0 - 6}
2015-08-03 11:02:21.662 TableViewSample[324:90811] Will Display Cell {length = 2, path = 0 - 7}
2015-08-03 11:02:21.664 TableViewSample[324:90811] Will Display Cell {length = 2, path = 0 - 8}
2015-08-03 11:02:21.666 TableViewSample[324:90811] Will Display Cell {length = 2, path = 0 - 9}
2015-08-03 11:02:21.669 TableViewSample[324:90811] Will Display Cell {length = 2, path = 0 - 10}
2015-08-03 11:02:21.671 TableViewSample[324:90811] Will Display Cell {length = 2, path = 0 - 11}
2015-08-03 11:02:21.990 TableViewSample[324:90811] Did End Display Cell {length = 2, path = 0 - 0}
2015-08-03 11:02:21.991 TableViewSample[324:90811] Did End Display Cell {length = 2, path = 0 - 1}
2015-08-03 11:02:21.992 TableViewSample[324:90811] Did End Display Cell {length = 2, path = 0 - 2}
2015-08-03 11:02:21.992 TableViewSample[324:90811] Did End Display Cell {length = 2, path = 0 - 3}
2015-08-03 11:02:21.993 TableViewSample[324:90811] Did End Display Cell {length = 2, path = 0 - 4}
2015-08-03 11:02:21.994 TableViewSample[324:90811] Did End Display Cell {length = 2, path = 0 - 5}
2015-08-03 11:02:21.994 TableViewSample[324:90811] Did End Display Cell {length = 2, path = 0 - 6}
2015-08-03 11:02:21.995 TableViewSample[324:90811] Did End Display Cell {length = 2, path = 0 - 7}
2015-08-03 11:02:21.995 TableViewSample[324:90811] Did End Display Cell {length = 2, path = 0 - 8}
2015-08-03 11:02:21.996 TableViewSample[324:90811] Did End Display Cell {length = 2, path = 0 - 9}
2015-08-03 11:02:21.997 TableViewSample[324:90811] Did End Display Cell {length = 2, path = 0 - 10}
2015-08-03 11:02:21.997 TableViewSample[324:90811] Did End Display Cell {length = 2, path = 0 - 11}
ReloadRow
2015-08-03 11:03:00.012 TableViewSample[324:90811] Did Highlight Cell {length = 2, path = 0 - 3}
2015-08-03 11:03:00.015 TableViewSample[324:90811] Did Select Cell {length = 2, path = 0 - 3}
2015-08-03 11:03:00.907 TableViewSample[324:90811] Asking Number of Sections in TableView
2015-08-03 11:03:00.908 TableViewSample[324:90811] Asking Number of Sections in TableView
2015-08-03 11:03:00.909 TableViewSample[324:90811] Asking Number of Rows in Section
2015-08-03 11:03:00.910 TableViewSample[324:90811] Will Display Cell {length = 2, path = 0 - 3}
2015-08-03 11:03:01.217 TableViewSample[324:90811] Did End Display Cell {length = 2, path = 0 - 3}
So, from the log: [UITableView reloadData] consumes 16ms. [UITableView reloadSections:withRowAnimation:] consumes 323ms. [UITableView reloadRowsAtIndexPaths:withRowAnimation:] consumes 302ms.
Question:
- Why [UITableView reloadData] is more efficient than reloadingSections even there is only one section?
- Why reloadingRowsAtIndexPaths takes that much of time, what actually takes the time?
- What kind of tools could help me verify or debug similar problems? and helper link reference if any?
- Thanks.
Solution
here, apple said:
Reloading a row causes the table view to ask its data source for a new cell for that row. The table animates that new cell in as it animates the old row out.
it seems that, when you call reloadrowsatindexpaths, a new cell will be initialized for the animation, while reloadData as we already knew, will reuse the cell before.
I think it can explain the question.