1

我知道这是一个常见的问题；但答案并不能满足我的要求。我试图在我的 tableview 单元格中有一个 mapView，我可以这样做；但是，当我滚动地图时，地图会重新开始重新加载，这会阻止平滑滚动。有人能帮帮我吗？这是来自 cellforrowatindexpath 的代码：

 - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:   (NSIndexPath *)indexPath object:(PFObject *)object
 {
static NSString *CellIdentifier = @"a";
FBGTimelineCell *cell = nil;
NSString *text = [object objectForKey:@"text"];
if (cell == nil) {
    cell =  [[FBGTimelineCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier detailText:text];
}

cell.selectionStyle = UITableViewCellSelectionStyleNone;
/*
cell.tableViewBackgroundColor = tableView.backgroundColor;
cell.contentView.backgroundColor = [UIColor whiteColor];
cell.backgroundColor = [UIColor whiteColor];
cell.cornerRadius = 2.0;
 [cell prepareForTableView:self.tableView indexPath:indexPath];
*/
UIView  *view = [[UIView alloc]initWithFrame:cell.frame];
view.layer.cornerRadius = 2;
view.layer.borderColor = [UIColor lightGrayColor].CGColor;
view.layer.borderWidth = 0.5;

view.backgroundColor = [UIColor whiteColor];
cell.backgroundView = view;

cell.backgroundColor = [UIColor clearColor];

NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
[formatter setDateFormat:@"dd MMM yyyy"];
cell.dateLabel.text = [NSString stringWithFormat:@"%@",[formatter stringFromDate:[object updatedAt]]];


cell.detailLabel.text = text;
cell.titleLabel.text = [object objectForKey:@"title"];


if ([[object objectForKey:@"isEvent"] integerValue] == 1) {
    cell.photoView.hidden = YES;
    PFQuery *query = [PFQuery queryWithClassName:@"Events"];
    [query whereKey:@"objectId" equalTo:[object objectForKey:@"event"]];
    query.cachePolicy = kPFCachePolicyCacheThenNetwork;
    [query findObjectsInBackgroundWithBlock:^(NSArray *objects, NSError *error){

        PFObject *object_event = [objects objectAtIndex:0];
    NSDate *date = [object_event objectForKey:@"date"];
    NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
    [formatter setDateFormat:@"MMM"];
    cell.eventMonthLabel.text = [[formatter stringFromDate:date] uppercaseString];
     [formatter setDateFormat:@"dd"];
    cell.eventDayLabel.text = [formatter stringFromDate:date];
    cell.eventInfoLabel.text = [object_event objectForKey:@"event"];
    NSString *str = [object_event objectForKey:@"details"];
        cell.eventDeatilsLabel.text = str;

    CGSize size2 = [[object objectForKey:@"text"] sizeWithFont:[UIFont fontWithName:@"Helvetica" size:13] constrainedToSize:CGSizeMake(275, 300) lineBreakMode:NSLineBreakByClipping];

    cell.backView.frame = CGRectMake(15, size2.height +58, 290, 150);

        self.mapView = [[MKMapView alloc]initWithFrame:CGRectMake(0, 150-65, 290, 65)];
        self.mapView.mapType = MKMapTypeStandard;
        [self.mapView setUserInteractionEnabled:NO];
        [self.mapView setZoomEnabled:NO];
        [self.mapView setScrollEnabled:NO];

        CALayer *capa = self.mapView.layer;


        //I'm reserving enough room for the shadow
        UIBezierPath *maskPath = [UIBezierPath bezierPathWithRoundedRect:self.mapView.bounds
                                                       byRoundingCorners:(UIRectCornerBottomLeft | UIRectCornerBottomRight)
                                                             cornerRadii:CGSizeMake(2.0, 2.0)];

        CAShapeLayer *maskLayer = [CAShapeLayer layer];
        maskLayer.frame = self.mapView.bounds;
        maskLayer.path = maskPath.CGPath;

        [capa addSublayer:maskLayer];
        capa.mask = maskLayer;
        [cell.backView addSubview:self.mapView];

    UIView *separator = [[UIView alloc]initWithFrame:CGRectMake(0, 150-65, 290, 1)];
    separator.backgroundColor = [UIColor colorWithHex:0xCBCBCB];
    [cell.backView addSubview:separator];

        UIButton *button = [UIButton buttonWithType:UIButtonTypeCustom];
        button.frame = CGRectMake(15, size2.height +58, 290, 150);
        button.backgroundColor = [UIColor clearColor];
        [button addTarget:self action:@selector(openEvent:) forControlEvents:UIControlEventTouchUpInside];
        [cell addSubview:button];

    self.mapView.delegate = self;

    MKCoordinateRegion viewRegion;
    MyLocation *location;
    PFGeoPoint *geo  =[object_event objectForKey:@"location"];
    CLLocationCoordinate2D coordinate =  CLLocationCoordinate2DMake(geo.latitude, geo.longitude);
    location = [[MyLocation alloc]initWithName:nil address:nil coordinate:coordinate];
    viewRegion = MKCoordinateRegionMakeWithDistance(coordinate, 1.0*METERS_PER_MILE, 1.0*METERS_PER_MILE);
    [self.mapView addAnnotation:location];

    //(41.06783368386694, 29.034912586212158)

            [self.mapView setRegion:viewRegion animated:NO];




    }];


}else{
if ([[object objectForKey:@"isPhoto"] integerValue] == 1) {
    PFFile *theImage = [object objectForKey:@"photo"];
    cell.photoView.backgroundColor = [UIColor darkGrayColor];
    cell.backView.hidden = YES;
    if (object) {
        cell.photoView.file = [object objectForKey:@"photo"];


        // PFQTVC will take care of asynchronously downloading files, but will only load them when the tableview is not moving. If the data is there, let's load it right away.
        if ([cell.photoView.file isDataAvailable]) {
            [cell.photoView loadInBackground];
        }
    }

    NSData *imageData = [theImage getData];
    UIImage *image = [UIImage imageWithData:imageData];
    cell.photoView.userInteractionEnabled = YES;
    cell.photoView.frame = CGRectMake(cell.photoView.frame.origin.x, cell.photoView.frame.origin.y, cell.photoView.frame.size.width, [self frameForImage:image inImageViewAspectFit:cell.photoView].size.height);
}else{
    if ([[object objectForKey:@"isVideo"] integerValue] == 1) {
        cell.photoView.frame = CGRectMake(cell.photoView.frame.origin.x, cell.photoView.frame.origin.y, cell.photoView.frame.size.width, 175);
        cell.photoView.backgroundColor = [UIColor darkGrayColor];
        cell.photoView.contentMode = UIViewContentModeScaleAspectFit;

        playButton = [UIButton buttonWithType:UIButtonTypeCustom];

        cell.backView.hidden = YES;
        [playButton setImage:[UIImage imageNamed:@"play_button.png"] forState:UIControlStateNormal];
        playButton.frame = cell.photoView.frame;
        [cell addSubview:playButton];
        if ([object objectForKey:@"photo"]) {
                                    NSLog(@"das");
            cell.photoView.file = [object objectForKey:@"photo"];

            [cell.photoView loadInBackground];
            cell.photoView.contentMode = UIViewContentModeScaleToFill;
        }



         url = [NSURL URLWithString:[object objectForKey:@"video"]];
        [HCYoutubeParser thumbnailForYoutubeURL:url thumbnailSize:YouTubeThumbnailDefaultMaxQuality completeBlock:^(UIImage *image, NSError *error) {

            if (!error) {
                if (![object objectForKey:@"photo"] ) {
                NSData *imageData = UIImageJPEGRepresentation(image, 1.0f);
                PFFile *imageFile = [PFFile fileWithName:@"videoImage.jpg" data:imageData];
                    NSLog(@"afsa");
                    [object setObject:imageFile forKey:@"photo"];
                    [object saveInBackground];
                    cell.photoView.image = image;

                }

                [playButton addTarget:self action:@selector(playVideo:) forControlEvents:UIControlEventTouchUpInside];



            }
            }];

        cell.photoView.userInteractionEnabled = YES;


    }else
    cell.photoView.hidden = YES;
}
}




return cell;

}

4

2 回答 2

1

UITableView滚动速度取决于您将数据转换为像素的速度。亲爱的macintosh你有很多绘图代码吗！

你能做什么？

你可以做各种各样的事情来让你的单元格渲染得更快：使用 绘制单元格CoreGraphics，积极缓存它们，或者简化它们。根据经验，避免复杂的 UI 元素层次结构。

创建一个NSDateFormatter可能需要半秒。创建一次，然后保存对它的引用，或者使用共享的“工厂”来存储和创建NSDateFormatter实例。

滚动也有可能MKMapView与您的滚动竞争UITableView。禁用滚动MKMapView。

如果我没有告诉您您使用的块可能包含对旧单元格的引用以维护特定的上下文/范围，那我会感到不妥。这个额外的（潜在strong的）引用将单元格保留在内存中几秒钟。

哦，拍摄，这些都不起作用！

尝试使用从屏幕外CoreGraphics获取 a 。确保您不是每次都实例化一个新的，因为这可能很昂贵。UIImage MKMapView

// Untested

UIGraphicsBeginImageContextWithOptions(_mapView.frame.size, YES, 0);
CGContextRef context = UIGraphicsGetCurrentContext();

CGAffineTransform flipVertical = CGAffineTransformMake( 1, 0, 0, -1, 0, _mapView.frame.size.height);
CGContextConcatCTM(context, flipVertical);  

[_mapView.layer renderInContext:context];

UIImage *renderedImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
// Do stuff with renderedImage

该图像可以无限期地缓存，地图不会经常更改。

如果你真的想变得花哨，你可以创建一个共享实例来保存它MKMapView并渲染地图的一部分。您可能会挂接到地图图块渲染中，MKMapView而不是使用上面的代码。

更新：（6.24.14）

在 iOS 7 中，您可以使用一个专门的类（您不再需要坚持MKMapView）来渲染地图，请参阅我刚刚写的这个 Gist：

https://gist.github.com/fhsjaagshs/2e0471b41bb7666efa7d

这种方法更好，因为你不需要坚持 a MKMapView，你不需要编写任何可能很慢的绘图代码（CoreGraphics是基于 CPU 的绘图，MKMapSnapshotter可能是基于 GPU 的），而且它是异步的！您可以将 aUIActivityIndicatorView放入您的单元格，当回调加载时，将其杀死并替换为UIImage.

于 2013-08-10T22:55:00.233 回答
0

尽量避免在下一行之外分配任何视图/对象。

if (cell == nil) {
    cell =  [[FBGTimelineCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier detailText:text];

    // Set Cell background View

    // Create Map View Here

    if(!self.mapview)
    {
        // Alloc Here.
    }
}
于 2013-06-15T02:00:13.083 回答