如标题中所述，
滚动tableview时会有一点延迟。
最奇怪的是，出列单元格占用了大部分的运行时间。
http://i.stack.imgur.com/qH8Lw.jpg
ShareTableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:@"Cell" forIndexPath:indexPath];
Share *share = [shares objectAtIndex:[indexPath row]];
[[cell profileImageView] sd_setImageWithURL:[NSURL URLWithString:[SERVER stringByAppendingString:[share profileImage]]] forState:UIControlStateNormal placeholderImage:[UIImage imageNamed:@"PlaceHolder"] completed:^(UIImage *image, NSError *error, SDImageCacheType cacheType, NSURL *imageUrl){
dispatch_async(dispatch_get_global_queue(QOS_CLASS_BACKGROUND, 0), ^{
UIImage *newImage;
if ([image size].width > [image size].height){
CGImageRef cropped = CGImageCreateWithImageInRect([image CGImage], CGRectMake([image size].width/2.0f-[image size].height/2.0f, 0, [image size].height, [image size].height));
newImage = [UIImage imageWithCGImage:cropped scale:[image scale] orientation:[image imageOrientation]];
CGImageRelease(cropped);
} else if ([image size].width < [image size].height){
CGImageRef cropped = CGImageCreateWithImageInRect([image CGImage], CGRectMake(0, [image size].height/2.0f-[image size].width/2.0f, [image size].width, [image size].width));
newImage = [UIImage imageWithCGImage:cropped scale:[image scale] orientation:[image imageOrientation]];
CGImageRelease(cropped);
} else if (image == nil){
newImage = [UIImage imageNamed@"PlaceHolder"];
} else {
newImage = image;
}
dispatch_async(dispatch_get_main_queue(), ^{
[[cell profileImageView] setImage:newImage forState:UIControlStateNormal];
});
});
}];
[[cell usernameLabel] setTitle:[share userName] forState:UIControlStateNormal];
//Date
{
static NSDateFormatter *formatter;
if (!formatter)
formatter = [[NSDateFormatter alloc] init];
if ([[share date] isToday]){
[formatter setDateFormat:@"hh:mm a"];
[[cell dateLabel] setText:[NSString stringWithFormat:@"Today, %@", [formatter stringFromDate:[share date]]]];
} else if ([[share date] isYesterday]){
[formatter setDateFormat:@"hh:mm a"];
[cell.dateLabel setText:[NSString stringWithFormat:@"Yesterday, %@", [formatter stringFromDate:[share date]]]];
} else {
[formatter setDateFormat:@"MMM dd, YYYY"];
[[cell dateLabel] setText:[formatter stringFromDate:[share date]]];
}
}
[[cell titleLabel] setText:[share title]];
if (![[share hashtag] isEqualToString:@""])
[[cell tagLabel] setText:[NSString stringWithFormat:@"#%@", [share hashtag]]];
else
[[cell tagLabel] setText:@""];
[[cell contentsLabel] setText:nil];
[[cell contentsLabel] setText:[NSString stringWithFormat:@"\u200B%@", [share comment]]];
[[cell contentsLabel] setDataDetectorTypes:UIDataDetectorTypeLink];
[[[cell scrollView] subviews]
makeObjectsPerformSelector:@selector(removeFromSuperview)];
if ([[share photos] count] != 0){
CGFloat x = 0;
CGRect bound = [[UIScreen mainScreen] bounds];
for (NSString *photo in [share photos]){
UIButton *imageButton = [UIButton buttonWithType:UIButtonTypeCustom];
[imageButton setFrame:CGRectMake(x, 0, bound.size.width-20.0f, (bound.size.width-20.0f)*3.0f/4.0f)];
[SDWebImageDownloader.sharedDownloader downloadImageWithURL:[NSURL URLWithString:[SERVER stringByAppendingString:photo]]
options:0
progress:^(NSInteger receivedSize, NSInteger expectedSize)
{
// progression tracking code
}
completed:^(UIImage *image, NSData *data, NSError *error, BOOL finished)
{
if (image && finished)
{
dispatch_async(dispatch_get_global_queue(QOS_CLASS_BACKGROUND, 0), ^{
CGRect bound = [[UIScreen mainScreen] bounds];
CGSize newSize = CGSizeMake(bound.size.width-20.0f, (bound.size.width-20.0f)*3.0f/4.0f);
UIImage *newImage;
if ([image size].height > [image size].width/4.0f*3.0f){
CGImageRef cropped = CGImageCreateWithImageInRect([image CGImage], CGRectMake(0, image.size.height/2.0f-([image size].width/4.0f*3.0f)/2.0f, [image size].width, [image size].width/4.0f*3.0f));
UIImage *old = [UIImage imageWithCGImage:cropped scale:[image scale] orientation:[image imageOrientation]];
CGImageRelease(cropped);
UIGraphicsBeginImageContextWithOptions(newSize, NO, 0.0);
[old drawInRect:CGRectMake(0, 0, newSize.width, newSize.height)];
newImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
} else if ([image size].height/3.0f*4.0f < [image size].width){
CGImageRef cropped = CGImageCreateWithImageInRect([image CGImage], CGRectMake(image.size.width/2.0f-([image size].height/3.0f*4.0f)/2.0f, 0, [image size].height/3.0f*4.0f, [image size].height));
UIImage *old = [UIImage imageWithCGImage:cropped scale:[image scale] orientation:[image imageOrientation]];
CGImageRelease(cropped);
UIGraphicsBeginImageContextWithOptions(newSize, NO, 0.0);
[old drawInRect:CGRectMake(0, 0, newSize.width, newSize.height)];
newImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
} else {
UIGraphicsBeginImageContextWithOptions(newSize, NO, 0.0);
[image drawInRect:CGRectMake(0, 0, newSize.width, newSize.height)];
newImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
}
dispatch_async(dispatch_get_main_queue(), ^{
[imageButton setImage:newImage forState:UIControlStateNormal];
});
});
}
}];
[imageButton setTag:[indexPath row]];
[imageButton addTarget:self action:@selector(showImage:) forControlEvents:UIControlEventTouchUpInside];
[[cell scrollView] addSubview:imageButton];
x += bound.size.width-20.0f;
}
[[cell scrollView] setContentSize:CGSizeMake(x, (bound.size.width-20.0f)/4.0f*3.0f)];
if (x > bound.size.width-20.0f) {
[[cell scrollView] setContentOffset:CGPointMake(10.0f, 0.0f)];
}
}
if ([share userLikedPost])
[[cell likeButton] setSelected:YES];
else
[[cell likeButton] setSelected:NO];
if ([share likeCount] == 0)
[[cell likedButton] setTitle:@"Liked" forState:UIControlStateNormal];
else
[[cell likedButton] setTitle:[NSString stringWithFormat:@"%d", [share likeCount]] forState:UIControlStateNormal];
if ([share reviewCount] == 0)
[[cell answerButton] setTitle:@"Comments" forState:UIControlStateNormal];
else
[[cell answerButton] setTitle:[NSString stringWithFormat:@"%d", [share reviewCount]] forState:UIControlStateNormal];
//Setup Targets
{
if ([[[cell usernameLabel] allTargets] count] == 0)
[[cell usernameLabel] addTarget:self action:@selector(showUserShares:) forControlEvents:UIControlEventTouchUpInside];
if ([[[cell profileImageView] allTargets] count] == 0)
[[cell profileImageView] addTarget:self action:@selector(showUserShares:) forControlEvents:UIControlEventTouchUpInside];
if ([[[cell likeButton] allTargets] count] == 0)
[[cell likeButton] addTarget:self action:@selector(likePressed:) forControlEvents:UIControlEventTouchUpInside];
if ([[[cell likedButton] allTargets] count] == 0)
[[cell likedButton] addTarget:self action:@selector(showWhoLiked:) forControlEvents:UIControlEventTouchUpInside];
if ([[[cell answerButton] allTargets] count] == 0)
[[cell answerButton] addTarget:self action:@selector(reviewPressed:) forControlEvents:UIControlEventTouchUpInside];
if ([[[cell moreButton] allTargets] count] == 0)
[[cell moreButton] addTarget:self action:@selector(morePressed:) forControlEvents:UIControlEventTouchUpInside];
}
[cell setTag:indexPath.row];
return cell;
我有什么遗失的吗？