使用MJRefresh实现今日头条下拉刷新

MJRefresh

MJRefresh

 - (void)viewDidLoad
{
    [super viewDidLoad];
    
    __unsafe_unretained UITableView *tableView = self.tableView;
    
    // 下拉刷新
    tableView.mj_header= [MJRefreshNormalHeader headerWithRefreshingBlock:^{
        
        
        // 模拟延迟加载数据，因此2秒后才调用（真实开发中，可以移除这段gcd代码）
        dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(2.0 * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{
            
            
            [self afterLoadDataAnimation:tableView viewHight:30 title:@"想显示什么就填什么"];
        });
    }];
}

- (void)afterLoadDataAnimation:(UIScrollView*)scrollview viewHight:(CGFloat)height title:(NSString*)title{
    // 设置自动切换透明度(在导航栏下面自动隐藏)
    scrollview.mj_header.automaticallyChangeAlpha = YES;
    // 结束刷新
    NSLog(@"%f",scrollview.mj_offsetY);//默认值是-118
    NSLog(@"%f",scrollview.mj_header.mj_h);//默认是54
    [UIView animateWithDuration:0.25 animations:^{
        scrollview.mj_offsetY = -(64 + height);//注意适配iPhone X导航栏高度
    }completion:^(BOOL finished) {
        
         __block UILabel *lable;
         __block UIView *view;
        
        for (int i = 0; i < scrollview.mj_header.subviews.count; i++) {
            if (i == scrollview.mj_header.subviews.count - 2 && scrollview.mj_header.subviews[scrollview.mj_header.subviews.count - 2]) {
                view = scrollview.mj_header.subviews[scrollview.mj_header.subviews.count - 2];
            }else if (i == scrollview.mj_header.subviews.count - 1 && scrollview.mj_header.subviews[scrollview.mj_header.subviews.count - 1]){
                lable = scrollview.mj_header.subviews[scrollview.mj_header.subviews.count - 1];
            }
        }
        
        static dispatch_once_t onceToken;
        dispatch_once(&onceToken, ^{
            view = [UIView new];
            lable = [UILabel new];
            
            view.backgroundColor = [UIColor redColor];
            view.layer.anchorPoint = CGPointMake(0.5, 0.5);
            view.frame = CGRectMake([UIScreen mainScreen].bounds.size.width/2, scrollview.mj_header.mj_h - height, 1, height);
            
            
            lable.layer.anchorPoint = CGPointMake(0.5, 0.5);
            lable.frame = CGRectMake(0, scrollview.mj_header.mj_h - height, [UIScreen mainScreen].bounds.size.width, height);
            lable.textAlignment = NSTextAlignmentCenter;
            
            [scrollview.mj_header insertSubview:view atIndex:scrollview.mj_header.subviews.count];
            [scrollview.mj_header insertSubview:lable atIndex:scrollview.mj_header.subviews.count];
        });
        
        view.transform = CGAffineTransformIdentity;
        lable.text = title;
        [view setHidden:NO];
        [lable setHidden:NO];
        
        [UIView animateWithDuration:0.3 animations:^{
            view.transform = CGAffineTransformMakeScale([UIScreen mainScreen].bounds.size.width + 1, 1);
        } completion:^(BOOL finished) {
            
        }];
        
        dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(2 * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{
            
            [scrollview.mj_header endRefreshing];
            dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(0.25 * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{
                [view setHidden:YES];
                [lable setHidden:YES];
            });
            
        });
    }];
}