//
// ViewController.m
// 仿淘宝,上拉进入详情
//
// Created by Amydom on 16/11/22.
// Copyright © 2016年 Amydom. All rights reserved.
//
#import "ViewController.h"
@interface ViewController ()<UITableViewDelegate , UITableViewDataSource , UIScrollViewDelegate , UIWebViewDelegate>
@property (nonatomic , strong)UITableView *tableView;
@property (nonatomic , strong)UIWebView *webView;
@property (nonnull , strong)UILabel *headLab;
@end
@implementation ViewController
- (void)viewDidLoad {
[super viewDidLoad];
self.view.backgroundColor = [UIColor whiteColor];
[self createView];
}
- (void)createView{
_tableView = [[UITableView alloc]initWithFrame:self.view.bounds style:UITableViewStylePlain];
_tableView.delegate = self;
_tableView.dataSource = self;
_tableView.rowHeight = .f;
[self.view addSubview:_tableView];
[_tableView registerClass:[UITableViewCell class] forCellReuseIdentifier:@"cell"];
UILabel *footLabel = [[UILabel alloc]initWithFrame:CGRectMake(, , self.view.frame.size.width, )];
footLabel.text = @"继续拖动，查看图文详情";
footLabel.font = [UIFont systemFontOfSize:];
footLabel.textAlignment = NSTextAlignmentCenter;
_tableView.tableFooterView = footLabel;
//注意:懒加载时,只有用 self 才能调其 getter 方法
[self.view addSubview:self.webView];
_headLab = [[UILabel alloc] init];
_headLab.text = @"上拉，返回详情";
_headLab.textAlignment = NSTextAlignmentCenter;
_headLab.font = [UIFont systemFontOfSize:];
_headLab.frame = CGRectMake(, , self.view.frame.size.width, .f);
_headLab.alpha = .f;
_headLab.textColor = [UIColor blackColor];
[_webView addSubview:_headLab];
[ _webView.scrollView addObserver:self forKeyPath:@"contentOffset" options:NSKeyValueObservingOptionNew|NSKeyValueObservingOptionOld context:nil];
}
//懒加载 webView 增加流畅度
- (UIWebView *)webView{
//注意,这里不用 self 防止循环引用
if (!_webView) {
_webView = [[UIWebView alloc]initWithFrame:CGRectMake(, _tableView.contentSize.height, self.view.frame.size.width, self.view.frame.size.height)];
_webView.delegate = self;
_webView.delegate = self;
_webView.scrollView.delegate = self;
[_webView loadRequest:[NSURLRequest requestWithURL:[NSURL URLWithString:@"https://www.baidu.com"]]];
}
return _webView;
}
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section{
return ;
}
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath{
static NSString *indetifier = @"cell";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:indetifier];
cell.textLabel.text = @"Amydom";
return cell;
}
//监测 scroll 的偏移量
-(void)scrollViewDidEndDragging:(UIScrollView *)scrollView willDecelerate:(BOOL)decelerate
{
CGFloat offsetY = scrollView.contentOffset.y;
if([scrollView isKindOfClass:[UITableView class]]) // tableView界面上的滚动
{
// 能触发翻页的理想值:tableView整体的高度减去屏幕本省的高度
CGFloat valueNum = _tableView.contentSize.height - self.view.frame.size.height;
if ((offsetY - valueNum) > )
{
[self goToDetailAnimation]; // 进入图文详情的动画
}
}
else // webView页面上的滚动
{
if(offsetY < && -offsetY > )
{
[self backToFirstPageAnimation]; // 返回基本详情界面的动画
}
}
}
// 进入详情的动画
- (void)goToDetailAnimation
{
[UIView animateWithDuration:0.3 delay:0.0 options:UIViewAnimationOptionLayoutSubviews animations:^{
_webView.frame = CGRectMake(, , self.view.frame.size.width, self.view.frame.size.height);
_tableView.frame = CGRectMake(, -self.view.frame.size.height , self.view.frame.size.width, self.view.frame.size.height);
} completion:^(BOOL finished) {
}];
}
// 返回第一个界面的动画
- (void)backToFirstPageAnimation
{
[UIView animateWithDuration:0.3 delay:0.0 options:UIViewAnimationOptionLayoutSubviews animations:^{
_tableView.frame = CGRectMake(, , self.view.frame.size.width, self.view.bounds.size.height);
_webView.frame = CGRectMake(, _tableView.contentSize.height, self.view.frame.size.width, self.view.frame.size.height);
} completion:^(BOOL finished) {
}];
}
// KVO观察
- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary<NSKeyValueChangeKey,id> *)change context:(void *)context{
if(object == _webView.scrollView && [keyPath isEqualToString:@"contentOffset"])
{
[self headLabAnimation:[change[@"new"] CGPointValue].y];
}else
{
[super observeValueForKeyPath:keyPath ofObject:object change:change context:context];
}
}
// 头部提示文本动画
- (void)headLabAnimation:(CGFloat)offsetY
{
_headLab.alpha = -offsetY/;
_headLab.center = CGPointMake(self.view.frame.size.width/, -offsetY/.f);
// 图标翻转，表示已超过临界值，松手就会返回上页
if(-offsetY > ){
_headLab.textColor = [UIColor redColor];
_headLab.text = @"释放，返回详情";
}else{
_headLab.textColor = [UIColor blackColor];
_headLab.text = @"上拉，返回详情";
}
}
- (void)didReceiveMemoryWarning {
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
@end