我知道这是一个常见问题;但答案并不能满足我的要求。我试图在tableview单元格中有一个mapView，我可以这样做;但是当我滚动地图时再次重新加载会阻止平滑滚动。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;
}
答案 0 :(得分：1)
UITableView滚动速度取决于您将数据转换为像素的速度。甜蜜macintosh你有很多绘图代码!!
您可以执行各种操作以使您的单元格更快地渲染：使用CoreGraphics绘制单元格，积极缓存它们或简化它们。根据经验，避免使用复杂的UI元素层次结构。
创建NSDateFormatter可能需要半秒。创建一次，然后保存对它的引用，或使用共享的“工厂”来存储和创建NSDateFormatter实例。
MKMapView滚动也有可能与您的UITableView滚动竞争。禁用MKMapView上的滚动。
如果我没有告诉你，你使用的块可能包含对旧单元格的引用以维持某个上下文/范围，那么我会感到不舒服。这个额外的（可能strong）引用将单元格保留在内存中几秒钟。
尝试使用CoreGraphics从屏幕外 UIImage获取MKMapView。确保你每次都没有实例化新的，因为这可能很昂贵。
// 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
此图片可以无限期缓存，地图不会经常更改。
如果您真的想要获得幻想，可以创建一个包含此MKMapView的共享实例并渲染地图的一部分。您可以在MKMapView中挂钩到地图图块渲染，而不是使用上面的代码。
在iOS 7中，您可以使用专门的类（您不需要再持有MKMapView来渲染地图），请参阅我刚才写的这个Gist：
https://gist.github.com/fhsjaagshs/2e0471b41bb7666efa7d
这种方法更好，因为您不需要保留MKMapView，您不需要编写任何可能很慢的绘图代码（CoreGraphics是基于CPU的绘图，{{1可能是基于GPU的），它是异步的！您可以将MKMapSnapshotter放入您的单元格中，当回调加载时，将其删除并将其替换为UIActivityIndicatorView。
答案 1 :(得分：0)
尽量避免在以下行中分配视图/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.
}
}