🌹向下滑动Tableview显示导航🌹

困难是成功的阶梯，爬着很累，但不能轻言放弃。
把经验藏在肚子里的人，不会成功

首先在AppDelegate.m中

#import "AppDelegate.h"
#import "ViewController.h"
@interface AppDelegate ()
@end
@implementation AppDelegate
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
//创建导航    
    ViewController *vv=[[ViewController alloc]init];
    UINavigationController *nav=[[UINavigationController alloc]initWithRootViewController:vv];
    self.window.rootViewController=nav;
    
    return YES;
}

之后再ViewController.m中

#import "ViewController.h"
#define IPHONE_WIDTH  [UIScreen mainScreen].bounds.size.width
#define IPHONE_HEIGHT [UIScreen mainScreen].bounds.size.height
@interface ViewController ()<UITableViewDelegate,UITableViewDataSource>
{
    UITableView * table;
    UIView * _myNavigationView;
}
@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];

    self.navigationItem.title =@"向下滑动表格显示导航";
    self.view.backgroundColor =[UIColor blackColor];
    
    table = [[UITableView alloc]initWithFrame:CGRectMake(0, 0, self.view.frame.size.width, self.view.frame.size.height) style:UITableViewStyleGrouped];
    table.backgroundColor =[UIColor whiteColor];
    table.delegate =self;
    table.dataSource =self;
    [self.view addSubview:table];
    [self.navigationController.navigationBar setBackgroundImage:[[UIImage alloc] init] forBarMetrics:UIBarMetricsDefault];
    [self.navigationController.navigationBar setShadowImage:[[UIImage alloc] init]];
    
    _myNavigationView = [[UIView alloc] initWithFrame:CGRectMake(0, 0, IPHONE_WIDTH, 64)];
    _myNavigationView.backgroundColor = [UIColor redColor];
    
    [self.view addSubview:_myNavigationView];
}
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section;
{
    return 30;
}
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath;
{
    static NSString * cellID =@"cell";
    UITableViewCell * cell = [tableView dequeueReusableCellWithIdentifier:cellID];
    if (!cell)
    {
        cell =[[UITableViewCell alloc]initWithStyle:UITableViewCellStyleSubtitle reuseIdentifier:cellID];
    }
    return cell;
}
-(CGFloat)tableView:(UITableView *)tableView heightForHeaderInSection:(NSInteger)section
{
    return 1;
}
- ( UIView *)tableView:(UITableView *)tableView viewForHeaderInSection:(NSInteger)section;
{
    return nil;
}
- ( UIView *)tableView:(UITableView *)tableView viewForFooterInSection:(NSInteger)section;
{
    return nil;
}

#pragma mark - scroll Delegate
//重要的东西都在这个方法里
- (void)scrollViewDidScroll:(UIScrollView *)scrollView
{
    int contentOffSetY = scrollView.contentOffset.y;
    
    if (contentOffSetY< 64)
    { _myNavigationView.alpha= scrollView.contentOffset.y/64; }
    else
    {
        _myNavigationView.alpha=1;
    }
    if (contentOffSetY<0)
    {
//        突然滑动的并且幅度很大的请款下 会在原本的导航view上面64的高度   
        //        CGRect rect =_myNavigationView.frame; rect.origin.y =0;
        //        rect.size.height=-contentOffSetY+64;
        //        _myNavigationView.frame =rect;
    }   
}
@end

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