Ios UICollectionView滚动性能差
我遇到的问题是,每当一行消失在视野之外时,滚动就会有一个非常快且很短的延迟 这是我的代码:Ios UICollectionView滚动性能差,ios,objective-c,core-data,uicollectionview,uicollectionviewcell,Ios,Objective C,Core Data,Uicollectionview,Uicollectionviewcell,我遇到的问题是,每当一行消失在视野之外时,滚动就会有一个非常快且很短的延迟 这是我的代码: - (UICollectionViewCell *)collectionView:(UICollectionView *)_collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath { UICollectionViewCell *cell = [self.collView dequeueReusableCellWithReuseI
- (UICollectionViewCell *)collectionView:(UICollectionView *)_collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath
{
UICollectionViewCell *cell = [self.collView dequeueReusableCellWithReuseIdentifier:@"cell" forIndexPath:indexPath];
Saints *note = nil;
int aX=0;
int aY=0;
note = [self.fetchedResultsController objectAtIndexPath:indexPath];
for (UIView *view in cell.contentView.subviews) {
if([view isKindOfClass:[UIImageView class]])
{
[view removeFromSuperview];
}
else if([view isKindOfClass:[UILabel class]])
{
[view removeFromSuperview];
}}
cell.backgroundColor = [UIColor clearColor];
UIImage *imgbackground = [UIImage imageNamed:@"today-left-side-images-bg.png"];
NSArray *messages = [[NSArray alloc] initWithObjects: @"random-saint-text-bg-brown.png",@"random-saint-text-bg-brightblue.png",@"random-saint-text-bg-green.png",@"random-saint-text-bg-grey.png",@"random-saint-text-bg-lightblue.png",@"random-saint-text-bg-lime.png",@"random-saint-text-bg-purple.png",@"random-saint-text-bg-red.png",@"random-saint-text-bg-teal.png",nil];
int randNum = arc4random() % [messages count];
NSString *returnValue = [messages objectAtIndex:randNum];
NSString *rndBGImg= returnValue;
UIImage *imgbackgroundlower = [UIImage imageNamed:rndBGImg];
UIImageView *imgViewlower = [[UIImageView alloc] initWithImage:imgbackgroundlower];
//imgViewlower.frame=CGRectMake(aX, aY+140, 140,73);
imgViewlower.frame=CGRectMake(aX+4, aY+114, 119,43);
UIImageView *imgView = [[UIImageView alloc] initWithImage:imgbackground];
imgView.frame=CGRectMake(aX, aY, 127,162);
UIImageView *imgSaintPic = [[UIImageView alloc]init];
imgSaintPic.tag=1;
imgSaintPic.frame=CGRectMake(aX+6, aY+6, 114,145);
//NSString *imgname = [aDic objectForKey:@"saint_image"];
NSString *imgname = note.saint_imagethumbnail;
UIImage *tempimg= [UIImage imageNamed:imgname];
[imgSaintPic setImage:tempimg];
UILabel *lblNamelocal=[[UILabel alloc]init];
NSString *strSaintName=note.saint_name;
//lblNamelocal.text=strSaintName;
if([note.saint_title length]>1)
lblNamelocal.text=[NSString stringWithFormat:@"%@ %@",note.saint_title,strSaintName];
else
lblNamelocal.text=[NSString stringWithFormat:@"%@",strSaintName];
//lblNamelocal.frame = CGRectMake(aX+6, aY+109, 116,30);
[lblNamelocal sizeToFit];
lblNamelocal.frame = CGRectMake(aX+5, aY+115, 118,26);
lblNamelocal.lineBreakMode = UILineBreakModeWordWrap;
lblNamelocal.numberOfLines = 0;
lblNamelocal.backgroundColor = [UIColor clearColor];
lblNamelocal.textColor = [UIColor whiteColor];
lblNamelocal.font = [UIFont fontWithName:@"HelveticaNeue-CondensedBold" size:11 ];
// lblNamelocal.textAlignment=UITextAlignmentLeft;
lblNamelocal.baselineAdjustment = UIBaselineAdjustmentAlignCenters;
lblNamelocal.shadowColor = [UIColor darkGrayColor];
lblNamelocal.shadowOffset = CGSizeMake(0,0.5);
lblNamelocal.textAlignment = UITextAlignmentCenter;
UILabel *lblsubtitle=[[UILabel alloc]init];
//NSString *strSaintSubtitle=[aDic objectForKey:@"saint_title"];
lblsubtitle.text=note.saint_subtitle;
//lblsubtitle.frame = CGRectMake(aX+6, aY+132, 116, 25);
lblsubtitle.frame = CGRectMake(aX+5, aY+140, 113, 20);
lblsubtitle.lineBreakMode = UILineBreakModeWordWrap;
lblsubtitle.numberOfLines = 2;
lblsubtitle.backgroundColor = [UIColor clearColor];
lblsubtitle.textColor = [UIColor whiteColor];
lblsubtitle.font = [UIFont fontWithName:@"HelveticaNeue" size:10];
// Removed CJamesRun lblsubtitle.textAlignment=UITextAlignmentLeft;
lblsubtitle.shadowColor = [UIColor darkGrayColor];
lblsubtitle.shadowOffset = CGSizeMake(0,0.5);
lblsubtitle.textAlignment = UITextAlignmentCenter;
imgViewlower.tag=3;
lblNamelocal.tag=2;
lblsubtitle.tag=4;
[cell.contentView addSubview:imgView];
[cell.contentView addSubview:imgSaintPic];
[cell.contentView addSubview:imgViewlower];
[cell.contentView addSubview:lblNamelocal];
[cell.contentView addSubview:lblsubtitle];
// cell.layer.masksToBounds = NO;
cell.layer.shouldRasterize = YES;
cell.layer.rasterizationScale = [UIScreen mainScreen].scale;
return cell;
}
我已经厌倦了栅格化单元层,以及在创建新单元时从SuperView中删除视图。
还有其他建议吗?我建议只设置一次单元格的子视图,然后只更新集合视图中的内容:cellForItemAtIndexPath:。例如,您正在每个单元格中加载一些图像,但这些图像对于每个单元格都是相同的,因此无需在每次重复使用该单元格时加载这些图像。要同意这个答案,他应该将UICollectionViewCell子类化,以便将其与视图一起设置。然后他可以设置适当的属性(图像视图的图像,标签的文本)。谢谢。这是一个很好的补充,是处理收集单元的正确方法。