Question

我基本上试图达到这个效果：http://youtu.be/VBW2i0P11iI

tableview是一个基本的视图，通过自动布局固定到它的超级视图。下面的视图添加了经典的insertSubview：belowSubview：/ addChildViewController组合。

我尝试了几种方法。我现在拥有的是：

＆＃13;

if (scrollOffset >= -scrollView.contentInset.top) {
        self.resultsTableViewContainerTopConstraint.constant = 0;
    } else {
        self.resultsTableViewContainerTopConstraint.constant = MAX(self.resultsTableViewContainerTopConstraint.constant, self.resultsTableViewContainerTopConstraint.constant - scrollDiff);
    }
}

＆＃13;

所以我基本上是根据contentOffset的delta更改顶部约束。这个问题是uitableview反弹，所以它总是进入if的第一个分支。但即使我解决了这个问题，我觉得我只是修补它。我确信这是一种更优雅的方式来实现具有相同响应性的视频中的效果。

任何建议都将不胜感激。感谢

Answer 1

我不确定这是不是你想要的，但我做了一个快速演示：

ViewController.h

#import <UIKit/UIKit.h>

@interface ViewController : UIViewController <UITableViewDataSource, UITableViewDelegate, UIScrollViewDelegate>

@property (nonatomic, strong) UIView *headerView;
@property (nonatomic, strong) UILabel *lblTitle;

@property (nonatomic, strong) UIButton *btnReset;

@property (nonatomic, strong) UIImageView *imageView;

@property (nonatomic, strong) UIScrollView *scrollView;
@property (nonatomic, strong) UITableView *tableView;

@property (nonatomic, strong) NSLayoutConstraint *scrollViewTopConstraint;

@end

ViewController.m

#import "ViewController.h"

@interface ViewController ()

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.

    //self.view.backgroundColor = [UIColor whiteColor];

    [self initViews];
    [self initConstraints];
}

- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

-(void)initViews
{
    self.view.backgroundColor = [UIColor colorWithRed:43.0/255.0 green:39.0/255.0 blue:55.0/255.0 alpha:1.0];

    self.scrollView = [[UIScrollView alloc] init];
    self.scrollView.backgroundColor = [UIColor clearColor];
    self.scrollView.alwaysBounceVertical = YES;
    self.scrollView.delegate = self;

    self.headerView = [[UIView alloc] init];
    self.headerView.backgroundColor = [UIColor colorWithRed:43.0/255.0 green:39.0/255.0 blue:55.0/255.0 alpha:1.0];
    self.headerView.layer.shadowColor = [UIColor blackColor].CGColor;
    self.headerView.layer.shadowOffset = CGSizeMake(0,0);
    self.headerView.layer.shadowOpacity = 0.25;
    self.headerView.layer.shadowRadius = 4;

    self.lblTitle = [[UILabel alloc] init];
    self.lblTitle.text = @"HEADER VIEW";
    self.lblTitle.textColor = [UIColor whiteColor];
    self.lblTitle.textAlignment = NSTextAlignmentCenter;

    self.btnReset = [[UIButton alloc] init];
    [self.btnReset setTitle:@"Reset" forState:UIControlStateNormal];
    self.btnReset.backgroundColor = [UIColor colorWithRed:0.75 green:0.0 blue:0.0 alpha:1.0];
    self.btnReset.layer.cornerRadius = 5.0;
    [self.btnReset addTarget:self action:@selector(resetView) forControlEvents:UIControlEventTouchUpInside];

    self.imageView = [[UIImageView alloc] init];
    self.imageView.backgroundColor = [UIColor colorWithRed:43.0/255.0 green:39.0/255.0 blue:55.0/255.0 alpha:1.0];

    self.tableView = [[UITableView alloc] init];
    self.tableView.delegate = self;
    self.tableView.dataSource = self;
    self.tableView.rowHeight = 150.0;
    self.tableView.layer.shadowColor = [UIColor blackColor].CGColor;
    self.tableView.layer.shadowOffset = CGSizeMake(0,-5);
    self.tableView.layer.shadowOpacity = 0.5;
    self.tableView.layer.shadowRadius = 20;
    self.tableView.backgroundColor = [UIColor clearColor];
    self.tableView.scrollEnabled = NO;
    self.tableView.clipsToBounds = NO;


    [self.headerView addSubview:self.lblTitle];
    [self.headerView addSubview:self.btnReset];

    [self.scrollView addSubview:self.tableView];

    [self.view addSubview:self.imageView];
    [self.view addSubview:self.scrollView];
    [self.view addSubview:self.headerView];

}

-(void)initConstraints
{
    self.scrollView.translatesAutoresizingMaskIntoConstraints = NO;
    self.headerView.translatesAutoresizingMaskIntoConstraints = NO;
    self.lblTitle.translatesAutoresizingMaskIntoConstraints = NO;
    self.btnReset.translatesAutoresizingMaskIntoConstraints = NO;
    self.imageView.translatesAutoresizingMaskIntoConstraints = NO;
    self.tableView.translatesAutoresizingMaskIntoConstraints = NO;

    id views = @{
                 @"scrollView": self.scrollView,
                 @"headerView": self.headerView,
                 @"lblTitle": self.lblTitle,
                 @"btnReset": self.btnReset,
                 @"imageView": self.imageView,
                 @"tableView": self.tableView
                 };

    [self.view addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"H:|[scrollView]|" options:0 metrics:nil views:views]];
    [self.view addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"V:[scrollView]" options:0 metrics:nil views:views]];

    [self.view addConstraint:[NSLayoutConstraint constraintWithItem:self.scrollView attribute:NSLayoutAttributeHeight relatedBy:NSLayoutRelationEqual toItem:self.view attribute:NSLayoutAttributeHeight multiplier:1.0 constant:0.0]];



    self.scrollViewTopConstraint = [NSLayoutConstraint constraintWithItem:self.scrollView attribute:NSLayoutAttributeTop relatedBy:NSLayoutRelationEqual toItem:self.view attribute:NSLayoutAttributeTop multiplier:1.0 constant:0.0];

    [self.view addConstraint:self.scrollViewTopConstraint];




    [self.view addConstraint:[NSLayoutConstraint constraintWithItem:self.scrollView attribute:NSLayoutAttributeHeight relatedBy:NSLayoutRelationEqual toItem:self.view attribute:NSLayoutAttributeHeight multiplier:1.0 constant:0.0]];

    [self.view addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"H:|[headerView(320)]|" options:0 metrics:nil views:views]];

    [self.view addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"V:|[headerView(50)]" options:0 metrics:nil views:views]];

    [self.scrollView addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"H:|[tableView(320)]|" options:0 metrics:nil views:views]];

    [self.scrollView addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"V:|-150-[tableView(300)]|" options:0 metrics:nil views:views]];

    [self.view addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"H:|[imageView(320)]|" options:0 metrics:nil views:views]];
    [self.view addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"V:|[imageView(320)]" options:0 metrics:nil views:views]];

    [self.headerView addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"H:|[lblTitle]|" options:0 metrics:nil views:views]];
    [self.headerView addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"V:|[lblTitle]|" options:0 metrics:nil views:views]];

    [self.headerView addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"H:[btnReset(80)]-5-|" options:0 metrics:nil views:views]];
    [self.headerView addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"V:|-8-[btnReset]-8-|" options:0 metrics:nil views:views]];
}

-(BOOL)prefersStatusBarHidden
{
    return YES;
}

#pragma mark - TableView Methods -

-(NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
    return 2;
}

-(UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
    static NSString *cellID = @"cell";

    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:cellID];

    if(cell == nil)
    {
        cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:cellID];
    }

    cell.backgroundColor = [UIColor colorWithRed:0.5 green:0.5 blue:0.5 alpha:1.0];

    return cell;
}

#pragma mark - ScrollView Delegate -

-(void)scrollViewDidScroll:(UIScrollView *)scrollView
{
    //NSLog(@"scrollView offset = %lf", scrollView.contentOffset.y);

    if(scrollView.contentOffset.y <= -145)
    {
        //self.scrollView.scrollEnabled = NO;

        self.scrollViewTopConstraint.constant = self.view.bounds.size.height;

        [UIView animateWithDuration:0.5 delay:0.0 options:UIViewAnimationOptionCurveEaseOut animations:^{

            [self.scrollView layoutIfNeeded];

        } completion:^(BOOL finished) {

        }];
    }
}

-(void)resetView
{
    self.scrollViewTopConstraint.constant = 0;

    [UIView animateWithDuration:0.5 delay:0.0 options:UIViewAnimationOptionCurveEaseIn animations:^{

        [self.scrollView layoutIfNeeded];

    } completion:^(BOOL finished) {

    }];
}

打开应用时会得到什么：

screenshot 1

然后向下拖动到边缘，视图将打开：

screenshot 2

按红色重置按钮将其重新启动：D

uitableview拖动屏幕外

1 个答案:

ViewController.h

ViewController.m