我在 Code Review 上发布了这个,但有人告诉我它作为一个 Stack Overflow 问题可能会更好,所以写这篇文章。
我有一个 UITableView,当用户点击该部分的标题时,我会“隐藏”该部分。我认为这是我想出的一个非常酷的实现,但事实证明,当这个部分被隐藏并且用户拉动刷新时,每次他们拉动刷新时(刷新完成后),大约 1-2MB 被添加到内存中。如果 UITableView 的部分没有隐藏并且它们拉动刷新,则不会分配额外的内存(正确的方式/行为)。我知道 1-2 MB 并不多,但它全部加起来。我在 Profiler 中找不到任何漏洞,所以这就是我来到这里的原因。
我可能忽略了某些事情或我的逻辑有缺陷,如果能提供任何帮助,我将不胜感激。抱歉下面的冗长代码:
更新:已解决的代码:
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
switch (section)
{
case 0:
{
return [self friendRequests];
}
case 1:
{
return [self friends];
}
default:
{
if (self.showingBlockedUsers == YES)
{
return [self blockedUsers];
}
else
{
return 0;
}
}
}
}
原始问题的旧代码:
- (void)refreshing:(UIRefreshControl *)refreshControl
{
[refreshControl beginRefreshing];
[UIApplication sharedApplication].networkActivityIndicatorVisible = YES;
NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:[NSURL URLWithString:@"http://foobar.com/test.plist"]];
request.cachePolicy = NSURLRequestReloadIgnoringLocalAndRemoteCacheData;
request.timeoutInterval = 5.0;
[NSURLConnection sendAsynchronousRequest:request
queue:[NSOperationQueue mainQueue]
completionHandler:
^(NSURLResponse *response, NSData *data, NSError *connectionError)
{
if (data)
{
NSPropertyListFormat format;
NSMutableDictionary *dictionary = [NSPropertyListSerialization propertyListWithData:data options:NSPropertyListImmutable format:&format error:nil];
self.tableDataSource = dictionary;
[self.tableView reloadData];
[refreshControl endRefreshing];
[UIApplication sharedApplication].networkActivityIndicatorVisible = NO;
}
}
}
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
UITableViewCell *cell;
NSString *identifier = @"cellIdentifier";
UILabel *userNameLabel = [self userNameLabel];
UIView *requestsView = [self requestsView];
UIButton *approveButton = [self approveButton];
UIButton *denyButton = [self denyButton];
UIImageView *profileImageView = [self profileImageView];
if (cell == nil)
{
cell = [[UITableViewCell alloc]initWithStyle:UITableViewCellStyleDefault reuseIdentifier:identifier];
cell.selectionStyle = UITableViewCellSelectionStyleDefault;
[requestsView addSubview:approveButton];
[requestsView addSubview:denyButton];
[cell.contentView addSubview:requestsView];
[cell.contentView addSubview:profileImageView];
[cell.contentView addSubview:userNameLabel];
}
if (indexPath.section == 0)
{
cell.selectionStyle = UITableViewCellSelectionStyleNone;
userNameLabel.frame = CGRectMake(82, 0, 167, 68);
approveButton.tag = indexPath.row;
denyButton.tag = indexPath.row;
NSArray *keys = [self.tableDataSource objectForKey:@"Requests"];
id aKey = [keys objectAtIndex:indexPath.row];
userNameLabel.text = [aKey objectForKey:@"User"];
NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:[NSURL URLWithString:[aKey objectForKey:@"URL"]]];
request.cachePolicy = NSURLRequestReloadIgnoringLocalAndRemoteCacheData;
request.timeoutInterval = 5.0;
if ([imageCache objectForKey:aKey])
{
profileImageView.image = [imageCache objectForKey:aKey];
}
else
{
[NSURLConnection sendAsynchronousRequest:request
queue:[NSOperationQueue mainQueue]
completionHandler:
^(NSURLResponse *response, NSData *data, NSError *error)
{
if (data)
{
dispatch_async(dispatch_get_main_queue(), ^
{
profileImageView.image = [UIImage imageWithData:data];
[imageCache setObject:[UIImage imageWithData:data] forKey:aKey];
});
}
else
{
profileImageView.image = [self profileImage];
}
}];
}
}
else if (indexPath.section == 1)
{
requestsView.hidden = YES;
NSArray *keys = [self.tableDataSource objectForKey:@"Friends"];
id aKey = [keys objectAtIndex:indexPath.row];
userNameLabel.text = [aKey objectForKey:@"User"];
NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:[NSURL URLWithString:[aKey objectForKey:@"URL"]]];
request.cachePolicy = NSURLRequestReloadIgnoringLocalAndRemoteCacheData;
request.timeoutInterval = 5.0;
if ([imageCache objectForKey:aKey])
{
profileImageView.image = [imageCache objectForKey:aKey];
}
else
{
[NSURLConnection sendAsynchronousRequest:request
queue:[NSOperationQueue mainQueue]
completionHandler:
^(NSURLResponse *response, NSData *data, NSError *error)
{
if (data)
{
dispatch_async(dispatch_get_main_queue(), ^
{
profileImageView.image = [UIImage imageWithData:data];
[imageCache setObject:[UIImage imageWithData:data] forKey:aKey];
});
}
else
{
profileImageView.image = [self profileImage];
}
}];
}
}
else if (indexPath.section == 2)
{
requestsView.hidden = YES;
NSArray *keys = [self.tableDataSource objectForKey:@"Blocked"];
id aKey = [keys objectAtIndex:indexPath.row];
userNameLabel.text = [aKey objectForKey:@"User"];
}
return cell;
}
- (void)displayBlockedUsers
{
if (self.showingBlockedUsers == YES)
{
self.showingBlockedUsers = NO;
[self.tableView reloadSections:[NSIndexSet indexSetWithIndex:2] withRowAnimation:UITableViewRowAnimationNone];
}
else
{
self.showingBlockedUsers = YES;
[self.tableView reloadSections:[NSIndexSet indexSetWithIndex:2] withRowAnimation:UITableViewRowAnimationNone];
}
}
- (NSInteger)friendRequests
{
return [[self.tableDataSource objectForKey:@"Requests"]count];
}
- (NSInteger)friends
{
return [[self.tableDataSource objectForKey:@"Friends"]count];
}
- (NSInteger)blockedUsers
{
return [[self.tableDataSource objectForKey:@"Blocked"]count];
}
- (CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath
{
if (indexPath.section == 2 && self.showingBlockedUsers == NO)
{
return 0;
}
else
{
return 68;
}
}
- (CGFloat)tableView:(UITableView *)tableView heightForHeaderInSection:(NSInteger)section
{
if (section == 0)
{
if ([self friendRequests] < 1)
{
return 0;
}
else
{
return 22;
}
}
else if (section == 1)
{
if ([self friends] < 1)
{
return 0;
}
else
{
return 22;
}
}
else
{
if ([self blockedUsers] < 1)
{
return 0;
}
else
{
return 22;
}
}
}
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
switch (section)
{
case 0:
{
return [self friendRequests];
}
case 1:
{
return [self friends];
}
default:
{
return [self blockedUsers];
}
}
}
- (UIView *)tableView:(UITableView *)tableView viewForHeaderInSection:(NSInteger)section
{
UIView *headerView = [[UIView alloc]init];
headerView.backgroundColor = [UIColor colorWithRed:248.0/255.0 green:248.0/255.0 blue:248.0/255.0 alpha:1.0];
UILabel *headerLabel = [[UILabel alloc]initWithFrame:CGRectMake(12, 0, 320, 22)];
headerLabel.font = [UIFont systemFontOfSize:13.5];
[headerView addSubview:headerLabel];
if (section == 0)
{
NSInteger friendRequests = [self friendRequests];
if (friendRequests < 2)
{
headerLabel.text = [NSString stringWithFormat:@"%d Request",friendRequests];
}
else
{
headerLabel.text = [NSString stringWithFormat:@"%d Requests",friendRequests];
}
}
else if (section == 1)
{
NSInteger friends = [self friends];
if (friends < 2)
{
headerLabel.text = [NSString stringWithFormat:@"%d Friend",friends];
}
else
{
headerLabel.text = [NSString stringWithFormat:@"%d Friends",friends];
}
}
else
{
UIButton *theButton = [UIButton buttonWithType:UIButtonTypeCustom];
[theButton addTarget:self action:@selector(displayBlockedUsers) forControlEvents:UIControlEventTouchUpInside];
theButton.frame = CGRectMake(0, 0, 320, 22);
[headerView addSubview:theButton];
NSInteger blocked = [self blockedUsers];
if (self.showingBlockedUsers == YES)
{
headerLabel.text = [NSString stringWithFormat:@"%d Blocked - Tap to Hide",blocked];
}
else
{
headerLabel.text = [NSString stringWithFormat:@"%d Blocked - Tap to Show",blocked];
}
}
return headerView;
}
- (CGFloat)tableView:(UITableView *)tableView heightForFooterInSection:(NSInteger)section
{
return 0;
}
- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView
{
return 3;
}
最佳答案
您似乎通过在 heightForRowAtIndexPath:
中返回 0 来隐藏该部分。这种方法的问题在于表格 View 仍会创建这些单元格 - 因此除了为实际显示的所有单元格创建单元格之外,表格 View 还为所有被阻止的用户创建额外的单元格。
要隐藏一个部分,只需在部分“关闭”时从 tableView:numberOfRowsInSection:
返回 0
。这样, TableView 将不会调用 heightForRowAtIndexPath:
、cellForRowAtIndexPath:
或其他任何内容,因为您告诉它那里没有单元格。
关于ios - UITableView 'hidden' 部分导致每次拉动刷新时分配更多内存,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/21942603/