如何将 UIActivityIndicatorView 添加到 UITableView 的底部，并在加载时切换它答案

【问题标题】：How to add UIActivityIndicatorView to the bottom of UITableView, and toggle it on loadings如何将 UIActivityIndicatorView 添加到 UITableView 的底部，并在加载时切换它
【发布时间】：2016-11-11 11:09:06
【问题描述】：

我的UITableView 有“滚动加载更多”行为。当您滚动到底部时，它开始加载更多内容。我想要实现的是在服务调用正在进行时在 UITableView 底部显示UIActivityIndicatorView，并在添加新项目时隐藏它。

有什么好的方法可以解决这个问题？我正在使用 Swift，但也欢迎使用 Objective-C 解决方案。

【问题讨论】：

标签： ios objective-c swift xcode uitableview

【解决方案1】：

我在 Objective-C 中实现了相同的功能

在cellForRowAtIndexPath

if (indexPath.row == [self.yourArrayData count] - 1)
{
     // Call the API
     [self loadMoreData:@"all" andPages:[NSString stringWithFormat:@"%ld", (long)pages] AndIsLoadMore:YES];
}

添加加载器或设计

-(void)addLoaderViewAtBottom {
    viewLoader = [[UIView alloc] initWithFrame:CGRectMake(0, self.view.frame.size.height-100, self.view.frame.size.width, 50)];
    [viewLoader setBackgroundColor:[UIColor whiteColor]];
    [self.view addSubview:viewLoader];

    UIActivityIndicatorView *activityIndicator1 = [[UIActivityIndicatorView alloc] initWithActivityIndicatorStyle:UIActivityIndicatorViewStyleGray];
    activityIndicator1.center = CGPointMake((SCREEN_SIZE.width/2), 30);
    activityIndicator1.alpha = 1.0;
    activityIndicator1.hidden = NO;
    [viewLoader addSubview:activityIndicator1];

    [activityIndicator1 startAnimating];

}

-(void)hideLoaderView {
[UIView animateWithDuration:1
                 animations:^(void) {
                     [viewLoader setFrame:CGRectMake(0, self.view.frame.size.height, self.view.frame.size.width, 50)];

                 }];
}

然后在您的 API 调用方法中使用这两种方法。在 API 调用开始时调用 addLoaderViewAtBottom 并在收到响应后调用 hideLoaderView

编码愉快...

【讨论】：

【解决方案2】：

初始化UIActivityIndicatorView：

@interface MyBulletinVC ()
{
   UIActivityIndicatorView *activityLoadMore;
}

-(void)viewDidLoad 
{
   activityLoadMore = [[UIActivityIndicatorView alloc]initWithActivityIndicatorStyle:(UIActivityIndicatorViewStyleGray)];
}

检查UITableView 何时滚动以及content offset 是什么

- (void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView
{
   float bottomEdge = scrollView.contentOffset.y + scrollView.frame.size.height;
   float tblBottomEdge = _tblBulletin.frame.size.height+_tblBulletin.frame.origin.y;

   if (bottomEdge <= tblBottomEdge)
   {
      return;
   }

   if (bottomEdge >= scrollView.contentSize.height)
   {
      [self show_bottom_loader];
   }
}

如果适用于content offset，则在表的页脚中显示加载器：

-(void)show_bottom_loader
{
  _tblBulletin.tableFooterView = [self returnLoaderViewWhileFetchingRecords];
  CGPoint newContentOffset = CGPointMake(0, [_tblBulletin contentSize].height -  _tblBulletin.bounds.size.height);
  [_tblBulletin setContentOffset:newContentOffset animated:YES];
  [self getNewsRecords];
}

加载数据时隐藏页脚：

-(void)hide_bottom_loader
{
 _tblBulletin.tableFooterView = nil;
 UIView *v = [[UIView alloc] initWithFrame:CGRectZero];
 v.backgroundColor = [UIColor clearColor];
 [_tblBulletin setTableFooterView:v];
 [activityLoadMore stopAnimating];
}

-(UIView*)returnLoaderViewWhileFetchingRecords
{
  UIView *view  = [[UIView alloc]initWithFrame:CGRectMake(0,0,_tblBulletin.frame.size.width,44)];
  view.backgroundColor  =[UIColor clearColor];

  UILabel *lblBg =[[UILabel alloc]initWithFrame:CGRectMake(0,1,_tblBulletin.frame.size.width,42)];
  lblBg.backgroundColor  =[UIColor whiteColor];
  [view addSubview:lblBg];

  UILabel *lbl =[[UILabel alloc]initWithFrame:CGRectMake(_tblBulletin.frame.size.width/2 - 20,0,_tblBulletin.frame.size.width/2,view.frame.size.height)];
  lbl.textAlignment = NSTextAlignmentLeft;
  lbl.text = @"Loading...";
  lbl.font = [UIFont fontWithName:@"Arial" size:14.0f];
  lbl.textColor = [UIColor darkGrayColor];
  lbl.backgroundColor = [UIColor clearColor];
  lbl.userInteractionEnabled = NO;
  [view lbl];

  activityLoadMore.frame = CGRectMake(_tblBulletin.frame.size.width/2-35,22,0,0);
  [activityLoadMore startAnimating];
  [view addSubview:activityLoadMore];

  return view;
}

-(void)getNewsRecords  
{
    //fetch new records and add to your array.  
    [self hide_bottom_loader];  
    //reload table.
}

用你的表名替换tblBulletin。

【讨论】：