滑动图像 下拉效果

#import "ViewController.h"

 

#define ScreenWidth [[UIScreen mainScreen] bounds].size.width

#define Screenheight [[UIScreen mainScreen] bounds].size.height

#define kImageOriginHight 220

@interface ViewController ()<UITableViewDelegate,UITableViewDataSource>

 

@end

 

@implementation ViewController

{

    UIImageView *headerBg;

    UIVisualEffectView *visualEffectView;

}

@synthesize tableview;

- (void)viewDidLoad {

    [super viewDidLoad];

    // Do any additional setup after loading the view, typically from a nib.

    tableview.delegate = self;

    tableview.dataSource = self;

    headerBg = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"bg"]];

    headerBg.frame = CGRectMake(0, 0, ScreenWidth, kImageOriginHight);

    

//    UIVisualEffect *blurEffect;

//    blurEffect = [UIBlurEffect effectWithStyle:UIBlurEffectStyleLight];

//    

//    visualEffectView = [[UIVisualEffectView alloc] initWithEffect:blurEffect];

//    

//    visualEffectView.frame = headerBg.bounds;

//    [headerBg addSubview:visualEffectView];

    [tableview addSubview:headerBg];

    tableview.showsVerticalScrollIndicator = NO;

    UILabel *title = [[UILabel alloc] initWithFrame:CGRectMake(0, 100, ScreenWidth, 30)];

    title.textAlignment = NSTextAlignmentCenter;

    title.text = @"zhaozihui@gmail.com";

    [tableview addSubview:title];

 

}

 

- (void)didReceiveMemoryWarning {

    [super didReceiveMemoryWarning];

    // Dispose of any resources that can be recreated.

}

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section{

    return 10;

}

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath{

    static NSString * showUserInfoCellIdentifier = @"ShowUserInfoCell";

    UITableViewCell * cell = [tableView dequeueReusableCellWithIdentifier:showUserInfoCellIdentifier];

    if (cell == nil)

    {

        // Create a cell to display an ingredient.

        cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleSubtitle

                                       reuseIdentifier:showUserInfoCellIdentifier];

    }

    

    // Configure the cell.

    cell.textLabel.text=@"Test";

    return cell;

}

- (void)scrollViewDidScroll:(UIScrollView *)scrollView

{

    CGFloat yOffset  = scrollView.contentOffset.y;

 

    if (yOffset < 0) {

        CGRect f = headerBg.frame;

        f.origin.y = yOffset;

        f.size.height =  -yOffset + kImageOriginHight;

        f.origin.x = -(f.size.height*ScreenWidth/kImageOriginHight -  ScreenWidth)/2;

        f.size.width = f.size.height*ScreenWidth/kImageOriginHight;

        headerBg.frame = f;

        visualEffectView.frame = headerBg.bounds;

    }

}