本文主要展示一个demo实现UITableView的上拉加载数据；
先看看效果图：
接着上拉，加载更多数据：
主要实现的效果是在我们上拉结束拖拽之后，开始加载数据，数据加载的过程中有滚动轮提示用户正在加载，加载完成后滚动轮消失，加载的数据出现。直接看代码吧：
demo:
#import "ViewController.h"
@interface ViewController ()<UITableViewDataSource,UITableViewDelegate>{
UITableView *tableView;
//数据数组
NSMutableArray *dataArray;
//上拉时的加载数据
NSMutableArray *moreArray;
//数据数量
NSUInteger dataNumber;
//加载状态
BOOL loadMore;
}
@end
@implementation ViewController
- (void)viewDidLoad {
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
CGFloat width = self.view.frame.size.width;
CGFloat height = self.view.frame.size.height;
//创建Table
tableView = [[UITableView alloc] initWithFrame:(CGRect){,,width,height}];
tableView.dataSource = self;
tableView.delegate = self;
tableView.separatorStyle = UITableViewCellSeparatorStyleNone;
[self.view addSubview:tableView];
[self readySource];
//创建底部表格
[self creatFooterView];
}
//数据资源
- (void)readySource{
dataArray = [[NSMutableArray alloc] initWithObjects:@"数学", @"语文", @"英语", @"历史", @"地理", @"政治", @"物理", @"化学", @"生物", @"体育", @"音乐", @"美术", nil];
moreArray = [[NSMutableArray alloc] initWithObjects:@"Math", @"Chinese", @"English", @"History", nil];
}
//返回分组个数
- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView{
return ;
}
//返回每个分组中的行数
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section{
return dataArray.count;
}
- (UITableViewCell *)tableView:(UITableView *)TableView cellForRowAtIndexPath:(NSIndexPath *)indexPath{
//建立可重用标识符
static NSString *indentifier = @"UITableViewCell";
// NSString *indentifier = [NSString stringWithFormat:@"UITableViewCell%ld%ld",(long)indexPath.row,(long)indexPath.section];
UITableViewCell *cell = [TableView dequeueReusableCellWithIdentifier:indentifier];
if (!cell) {
cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:indentifier];
}
//移除所有子视图
[cell.subviews enumerateObjectsUsingBlock:^(id obj, NSUInteger idx, BOOL *stop) {
UIView *view = (UIView*)obj;
[view removeFromSuperview];
}];
//添加新视图
UILabel *title = [[UILabel alloc] initWithFrame:(CGRect){,,,}];
NSString *str = [dataArray objectAtIndex:indexPath.row];
title.text = str;
title.font = [UIFont systemFontOfSize:];
title.textColor = [UIColor blueColor];
[cell addSubview:title];
return cell;
}
//设置TableViewCell行高
- (CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath{
return ;
}
//开始加载
- (void)loadDataBegin{
if (loadMore == NO) {
loadMore = YES;
//设置滚动轮
UIActivityIndicatorView *activity = [[UIActivityIndicatorView alloc] initWithFrame:(CGRect){,,,}];
[activity setActivityIndicatorViewStyle:UIActivityIndicatorViewStyleGray];
[tableView.tableFooterView addSubview:activity];
[activity startAnimating];
[self loading];
}
}
//结束拖拽时调用得方法
- (void)scrollViewDidEndDragging:(UIScrollView *)scrollView willDecelerate:(BOOL)decelerate{
//设置范围，下拉到最底部时开始加载数据
if (!loadMore &&scrollView.contentOffset.y>(scrollView.contentSize.height-self.view.frame.size.height)) {
[self loadDataBegin];
}
}
//加载数据中
- (void)loading{
dataNumber = [dataArray count];
for (int i = ; i < moreArray.count; i++) {
[dataArray addObject:[moreArray objectAtIndex:i]];
}
[tableView reloadData];
[self loadDataEnd];
}
//结束加载
- (void)loadDataEnd{
loadMore = NO;
//结束加载创建底部表格
[self creatFooterView];
}
//创建底部表格
- (void)creatFooterView{
tableView.tableFooterView = nil;
UIView *footerView = [[UIView alloc] initWithFrame:(CGRect){,,self.view.frame.size.width,}];
footerView.backgroundColor = [UIColor colorWithWhite:0.9 alpha:];
UILabel *title = [[UILabel alloc] initWithFrame:(CGRect){,,self.view.frame.size.width,}];
title.text = @"上拉显示更多数据";
title.font = [UIFont systemFontOfSize:];
title.textAlignment = NSTextAlignmentCenter;
[footerView addSubview:title];
tableView.tableFooterView = footerView;
}