我从Parse.com后端加载数据,他们发给我一个使用可重复使用单元格的解决方案,但现在我仍然遇到加载速度的麻烦,这是我在tableview中的编码,我有一个子类用于制作我的单元格(ExploreStreamCustomCell.m)
- (ExploreStreamCustomCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
object:(PFObject *)object
{
static NSString *CellIdentifier = @"ExploreStreamCustomCell";
ExploreStreamCustomCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if (cell == nil) {
cell = [[ExploreStreamCustomCell alloc] initWithStyle:UITableViewCellStyleSubtitle
reuseIdentifier:CellIdentifier];
}
// Configure the cell
cell.listItemTitle.text = [object objectForKey:@"text"];
cell.checkinsLabel.text = [NSString stringWithFormat:@"%@", [object objectForKey:@"checkins"]];
cell.descriptionLabel.text = [object objectForKey:@"description"];
cell.selectionStyle = UITableViewCellSelectionStyleNone;
PFFile *listThumbnail = [object objectForKey:@"header"];
cell.listViewImage.image = [UIImage imageNamed:@"loading_image_stream.png"]; // placeholder image
cell.listViewImage.file = listThumbnail;
[cell.listViewImage loadInBackground:NULL];
return cell;
}
- (UITableViewCell *)tableView:(UITableView *)tableView cellForNextPageAtIndexPath:(NSIndexPath *)indexPath {
UITableViewCell *cell = [super tableView:tableView cellForNextPageAtIndexPath:indexPath];
cell.textLabel.font = [cell.textLabel.font fontWithSize:kPAWWallPostTableViewFontSize];
return cell;
}
如果我在单元格中拥有// configure单元格的所有内容== nil它的速度很快但它会显示9个独特数据行中的3个并重复这3个独特内容单元3次?
在ExploreStreamCustomCell.m中编辑额外代码
#import "ExploreStreamCustomCell.h"
@implementation ExploreStreamCustomCell
@synthesize listViewImage,
iconLocation,
iconPeople,
iconCheckins,
listItemTitle,
locationLabel,
peopleLabel,
checkinsLabel,
descriptionLabel,
listItemView;
- (id)initWithStyle:(UITableViewCellStyle)style reuseIdentifier:(NSString *)reuseIdentifier {
if(self = [super initWithStyle:style reuseIdentifier:reuseIdentifier]){
//Initialization code
listItemView = [[UIView alloc] init];
listViewImage = [[PFImageView alloc] init];
iconLocation = [[UIImageView alloc] init];
iconPeople = [[UIImageView alloc] init];
iconCheckins = [[UIImageView alloc] init];
listItemTitle = [[UILabel alloc] init];
locationLabel = [[UILabel alloc] init];
peopleLabel = [[UILabel alloc] init];
checkinsLabel = [[UILabel alloc] init];
descriptionLabel = [[UILabel alloc] init];
listViewImage.image = [UIImage imageNamed:@"nachtwacht_list_formaat.png"];
iconLocation.image = [UIImage imageNamed:@"icon_magenta_location.png"];
iconPeople.image = [UIImage imageNamed:@"icon_magenta_people.png"];
iconCheckins.image = [UIImage imageNamed:@"icon_magenta_checkins.png"];
listItemTitle.text = @"text";
locationLabel.text = @"0,7 km";
peopleLabel.text = @"34";
checkinsLabel.text = @"61";
descriptionLabel.text = @"Description text.";
[self.contentView addSubview:listItemView];
[self.contentView addSubview:listViewImage];
[self.contentView addSubview:iconLocation];
[self.contentView addSubview:iconPeople];
[self.contentView addSubview:iconCheckins];
[self.contentView addSubview:listItemTitle];
[self.contentView addSubview:locationLabel];
[self.contentView addSubview:peopleLabel];
[self.contentView addSubview:checkinsLabel];
[self.contentView addSubview:descriptionLabel];
}
return self;
}
- (void)layoutSubviews {
[super layoutSubviews];
CGRect contentRect = self.contentView.bounds;
CGFloat boundsX = contentRect.origin.x;
CGRect frame;
frame= CGRectMake(boundsX+0 , 33, 280, 124);
listViewImage.frame = frame;
listViewImage.contentMode = UIViewContentModeScaleAspectFill;
listViewImage.layer.masksToBounds = YES;
//listViewImage.backgroundColor = [UIColor lightGrayColor];
frame= CGRectMake(boundsX+20 , 164, 12, 18);
iconLocation.frame = frame;
//iconLocation.backgroundColor = [UIColor lightGrayColor];
frame= CGRectMake(boundsX+102 , 164, 24, 18);
iconPeople.frame = frame;
//iconPeople.backgroundColor = [UIColor lightGrayColor];
frame= CGRectMake(boundsX+193 , 164, 20, 16);
iconCheckins.frame = frame;
//iconLocation.backgroundColor = [UIColor lightGrayColor];
frame= CGRectMake(boundsX+0 , 0, 280, 33);
listItemView.frame = frame;
listItemView.backgroundColor = [UIColor colorWithRed:0.749 green:0.000 blue:0.243 alpha:1.000];
frame= CGRectMake(boundsX+20 , 3, 240, 29);
listItemTitle.frame = frame;
//listItemTitle.textColor = [UIColor colorWithRed:250.0f/255.0f green:194.0f/255.0f blue:9.0f/255.0f alpha:0.8f];
listItemTitle.textAlignment = UITextAlignmentLeft;
listItemTitle.font = [UIFont boldSystemFontOfSize:15];
listItemTitle.textColor = [UIColor whiteColor];
listItemTitle.backgroundColor = [UIColor clearColor];
listItemTitle.lineBreakMode = UILineBreakModeTailTruncation;
//listItemTitle.backgroundColor = [UIColor orangeColor];
frame= CGRectMake(boundsX+40 , 164, 57, 21);
locationLabel.frame = frame;
locationLabel.textAlignment = UITextAlignmentLeft;
locationLabel.font = [UIFont boldSystemFontOfSize:12];
locationLabel.textColor = [UIColor colorWithRed:0.749 green:0.000 blue:0.243 alpha:1.000];
locationLabel.backgroundColor = [UIColor clearColor];
locationLabel.lineBreakMode = UILineBreakModeTailTruncation;
locationLabel.numberOfLines = 1;
//locationLabel.backgroundColor = [UIColor redColor];
frame= CGRectMake(boundsX+134 , 164, 57, 21);
peopleLabel.frame = frame;
peopleLabel.textAlignment = UITextAlignmentLeft;
peopleLabel.font = [UIFont boldSystemFontOfSize:12];
peopleLabel.textColor = [UIColor colorWithRed:0.749 green:0.000 blue:0.243 alpha:1.000];
peopleLabel.backgroundColor = [UIColor clearColor];
peopleLabel.lineBreakMode = UILineBreakModeTailTruncation;
peopleLabel.numberOfLines = 1;
frame= CGRectMake(boundsX+221 , 164, 51, 21);
checkinsLabel.frame = frame;
checkinsLabel.textAlignment = UITextAlignmentLeft;
checkinsLabel.font = [UIFont boldSystemFontOfSize:12];
checkinsLabel.textColor = [UIColor colorWithRed:0.749 green:0.000 blue:0.243 alpha:1.000];
checkinsLabel.backgroundColor = [UIColor clearColor];
checkinsLabel.lineBreakMode = UILineBreakModeTailTruncation;
checkinsLabel.numberOfLines = 1;
frame= CGRectMake(boundsX+0 , 189, 280, 55);
descriptionLabel.frame = frame;
descriptionLabel.textAlignment = UITextAlignmentLeft;
descriptionLabel.font = [UIFont systemFontOfSize:13];
descriptionLabel.backgroundColor = [UIColor clearColor];
descriptionLabel.lineBreakMode = UILineBreakModeTailTruncation;
descriptionLabel.numberOfLines = 3;
}
- (void)setSelected:(BOOL)selected animated:(BOOL)animated {
[super setSelected:selected animated:animated];
// Configure the view for the selected state
}
/*
- (id)initWithFrame:(CGRect)frame
{
self = [super initWithFrame:frame];
if (self) {
// Initialization code
}
return self;
}
// Only override drawRect: if you perform custom drawing.
// An empty implementation adversely affects performance during animation.
- (void)drawRect:(CGRect)rect
{
// Drawing code
}
*/
@end
答案 0 :(得分:3)
探索代码效率低下的一个好方法是使用Instruments的Time Profiler工具。时间分析器将让您了解代码中逐行花费的时间。
我建议使用以下设置进行性能分析:
来自Apple的人脸检测示例应用程序:
然后你可以双击任何一行(更高的百分比意味着更多的时间用于该方法调用),以在代码中查看每个地方花费了多少时间。
从这里你可以开始弄清楚你效率低下的地方,看看究竟是什么占用了这么多时间。祝你好运!