UITableView reloadData，reloadSections的性能：withRowAnimation：和reloadRowsAtIndexPaths：withRowAnimation：

时间：2015-08-03 22:45:42

标签： ios objective-c uitableview reloaddata

我构建了一个测试目的应用程序，用于在重新加载表视图时测试这三种方法的性能。

enter image description here 

//
//  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

在调用三个方法时记录。

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}

所以，从日志中： [UITableView reloadData]消耗16毫秒。 [UITableView reloadSections：withRowAnimation：]消耗323ms。 [UITableView reloadRowsAtIndexPaths：withRowAnimation：]消耗302毫秒。

问题：

  • 为什么[UITableView reloadData]比reloadingSections更有效，即使只有一个部分？
  • 为什么reloadingRowsAtIndexPaths需要花费大量时间，实际需要花费多少时间？
  • 哪种工具可以帮助我验证或调试类似的问题？和辅助链接引用（如果有的话）？
  • 感谢。

1 个答案:

答案 0 :(得分：0)

here，苹果说：

  

重新加载行会导致表视图向其数据源询问该行的新单元格。该表动画了新单元格，因为它为旧行设置了动画。

看来，当你调用reloadrowsatindexpaths时，将为动画初始化一个新单元格，而我们已经知道的reloadData将重新使用该单元格。

我认为它可以解释这个问题。

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