像Snapchat这样的动画装载机

Question

我很想知道当你下拉刷新时,这个幽灵是什么？我想在我的应用程序中实现它,并想知道它是如何完成的.

Answer 1

我认为你需要编写自己的解决方案.但实际上并不那么难.

您需要创建一个包含可伸展图像的自定义表头视图,并在您的图像中实现一些处理UITableViewDelegate.下面是自定义刷新控件处理的相当通用的实现.

1)创建一个自定义UIView作为下拉指示器视图:

头文件:

#import <UIKit/UIKit.h>

typedef enum UpdateListViewState
{
    UpdateListViewStatePull,
    UpdateListViewStateRelease,
    UpdateListViewStateUpdate

}UpdateListViewState;


@interface UpdateListView : UIView
@property (nonatomic,readwrite) UpdateListViewState state;
@property (nonatomic,strong) UIImageView imageView;
@end

2)将headerView指定为tableView标头:

self.header = [[UpdateListView alloc] init];
self.table.tableHeaderView = self.header;

3)在你的UITableViewDelegate,实现表滚动处理:

const int UPDATE_DRAG_HEIGHT = -70; 

- (void)scrollViewWillEndDragging:(UIScrollView *)scrollView withVelocity:(CGPoint)velocity targetContentOffset:(inout CGPoint *)targetContentOffset 
{
    if (self.header.state == UpdateListViewStateRelease) {
       //Perform update stuff here & perhaps refresh animation
       self.header.state = UpdateListViewStateInitial;

    }
}

-(void)scrollViewDidScroll:(UIScrollView *)scrollView
{
    //adjust size of self.header.imageView here according to scrollView.ContentOffset
    if (scrollView.contentOffset.y < UPDATE_DRAG_HEIGHT && self.header.state != UpdateListViewStateUpdate) {
            self.header.state = UpdateListViewStateRelease;
    }
}