我在Code Review上发布了这个，但是被告知它可能会更好地作为Stack Overflow问题，所以这篇文章就这样了。
我有一个UITableView，当用户点击该部分的标题时，我正在“隐藏”一个部分。我认为这是我提出的一个非常酷的实现，但事实证明，当隐藏此部分并且用户进行刷新时，每次刷新时都会将大约1-2MB添加到内存中（刷新完成后）。如果未隐藏UITableView的部分并且它们进行刷新，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，但总而言之。我在Profiler中找不到任何泄漏，所以这就是我来到这里的原因。
我可能会忽视某些事情，或者我的逻辑存在缺陷，并会感谢所提供的任何帮助。对不起，下面是冗长的代码：
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;
}
答案 0 :(得分：5)
看起来你在heightForRowAtIndexPath:中返回0隐藏了该部分。这种方法的问题是表视图仍然会创建这些单元格 - 因此除了为实际显示的所有单元格创建单元格外，表格视图还为所有被阻止的用户创建了其他单元格。
要隐藏某个部分，只需在该部分“关闭”时从0返回tableView:numberOfRowsInSection:。这样，表格视图就不会调用heightForRowAtIndexPath:，cellForRowAtIndexPath:或其他任何内容，因为您告诉它那里没有单元格。
答案 1 :(得分：0)
好吧，快速查看它，它正在使用内存，因为cellForRowAtIndexPath:仍然被调用，你仍然将单元格返回，就好像它是可见的一样。这可能听起来很简单 ，但您是否尝试检查该部分是否隐藏，然后返回一个空单元格？
更新：问题在于您实际上并没有告诉表格视图您隐藏了单元格（只是降低了高度）。在MVC中，您的模型知道但控制器不。在您使用模型中的布尔值检查后，只需在- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section中返回0，看看您是否隐藏了单元格。