如果我有一个包含4行的UITableView,那么当我导航到该视图时,不应该调用4次cellForRowAtIndexPath方法吗？我发现它被多次调用,例如如果有4行,当我深入到UITable视图时会被调用8次,然后当我导航回到同一个UITableView时被调用12次.
我只是误解了这种方法的工作原理吗？我认为应该为显示的每一行调用一次(没有涉及滚动,因为表格视图的内容很容易适合我的iPad屏幕).
我应该注意到UITableView包含在iPad上的UISplitViewController的MasterViewController中.
编辑：我得到的真正问题是以下代码的应用方式不一致：
if (selectednavItem.folder.isAssignedToUser != [NSNumber numberWithInt:1]) { NSLog(@"%@",cell.textLabel.text); cell.selectionStyle = UITableViewCellSelectionStyleNone; cell.userInteractionEnabled = NO; cell.textLabel.enabled = NO; cell.detailTextLabel.text = @"Access not granted"; cell.detailTextLabel.enabled = NO; }
当我第一次“深入”到我的导航堆栈的特定级别时,事情就像他们应该的那样工作.但是后来如果我向上或向下导航,我发现各行被错误地处理,即当它们应该被启用时它们最终会被禁用.这导致我提出了一个断点和一些日志代码来试图找出发生了什么.我发现上面的代码被调用的次数比行数多 – 而且我记录的cell.textLabel.text值没有意义 – 同一行的值被多次记录 – 而其他行则没有记录在一起.
编辑：根据要求提供一些代码：
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
static Nsstring *CellIdentifier = @"FolderCell";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
[self configureCell:cell atIndexPath:indexPath];
return cell;
}
- (NSFetchedResultsController *)fetchedResultsController
{
if (__fetchedResultsController != nil) {
return __fetchedResultsController;
}
// Set up the fetched results controller.
// Create the fetch request for the entity.
NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
// Edit the entity name as appropriate.
NSEntityDescription *entity = [NSEntityDescription entityForName:@"NavItem" inManagedobjectContext:self.managedobjectContext];
[fetchRequest setEntity:entity];
// Set the batch size to a suitable number.
[fetchRequest setFetchBatchSize:20];
// Edit the sort keys as appropriate.
NSSortDescriptor *sortDescriptor1 = [[NSSortDescriptor alloc] initWithKey:@"sortOrder" ascending:YES];
NSSortDescriptor *sortDescriptor2 = [[NSSortDescriptor alloc] initWithKey:@"name" ascending:YES selector:@selector(localizedCaseInsensitiveCompare:)];
NSArray *sortDescriptors = [NSArray arrayWithObjects:sortDescriptor1,sortDescriptor2,nil];
[fetchRequest setSortDescriptors:sortDescriptors];
// Edit the section name key path and cache name if appropriate.
// nil for section name key path means "no sections".
NSFetchedResultsController *aFetchedResultsController = [[NSFetchedResultsController alloc] initWithFetchRequest:fetchRequest managedobjectContext:self.
managedobjectContext sectionNameKeyPath:nil cacheName:@"Master"];
aFetchedResultsController.delegate = self;
self.fetchedResultsController = aFetchedResultsController;
NSError *error = nil;
if (![self.fetchedResultsController performFetch:&error]) {
/*
Replace this implementation with code to handle the error appropriately.
abort() causes the application to generate a crash log and terminate. You should not use this function in a shipping application,although it may be useful during development.
*/
NSLog(@"Unresolved error %@,%@",error,[error userInfo]);
abort();
}
return __fetchedResultsController;
}
- (void)configureCell:(UITableViewCell *)cell atIndexPath:(NSIndexPath *)indexPath
{
NSManagedobject *managedobject = [self.fetchedResultsController objectAtIndexPath:indexPath];
NavItem *selectednavItem = (NavItem *)managedobject;
cell.textLabel.text = [[managedobject valueForKey:@"name"] description];
cell.detailTextLabel.text = @"";
if (selectednavItem.folder != nil) {
cell.imageView.image = [UIImage imageNamed:@"Folder.png"];
//NSLog(@"%@",selectednavItem.folder.isAssignedToUser);
if (selectednavItem.folder.isAssignedToUser != [NSNumber numberWithInt:1])
{
NSLog(@"%@",cell.textLabel.text);
cell.selectionStyle = UITableViewCellSelectionStyleNone;
cell.userInteractionEnabled = NO;
cell.textLabel.enabled = NO;
cell.detailTextLabel.text = @"Access not granted";
cell.detailTextLabel.enabled = NO;
}
}
else if (selectednavItem.document != nil) {
cell.detailTextLabel.text = [[selectednavItem.document valueForKey:@"itemDescription"] description];
if ([[selectednavItem.document.fileName pathExtension] isEqualToString:@"pdf"])
{
cell.imageView.image = [UIImage imageNamed:@"pdf.png"];
}
else if ([[selectednavItem.document.fileName pathExtension] isEqualToString:@"doc"] || [[selectednavItem.document.fileName pathExtension] isEqualToString:@"docx"])
{
cell.imageView.image = [UIImage imageNamed:@"Word-32x32.png"];
}
else if ([[selectednavItem.document.fileName pathExtension] isEqualToString:@"xls"] || [[selectednavItem.document.fileName pathExtension] isEqualToString:@"xlsx"])
{
cell.imageView.image = [UIImage imageNamed:@"Excel-32x32.png"];
}
else if ([[selectednavItem.document.fileName pathExtension] isEqualToString:@"ppt"] || [[selectednavItem.document.fileName pathExtension] isEqualToString:@"pps"])
{
cell.imageView.image = [UIImage imageNamed:@"Powerpoint-32x32.png"];
}
else if ([[selectednavItem.document.fileName pathExtension] isEqualToString:@"mp3"] || [[selectednavItem.document.fileName pathExtension] isEqualToString:@"wav"])
{
cell.imageView.image = [UIImage imageNamed:@"65-note.png"];
}
else if ([[selectednavItem.document.fileName pathExtension] isEqualToString:@"mp4"] || [[selectednavItem.document.fileName pathExtension] isEqualToString:@"mov"])
{
cell.imageView.image = [UIImage imageNamed:@"46-movie-2.png"];
}
else if ([[selectednavItem.document.fileName pathExtension] isEqualToString:@"ibooks"])
{
cell.imageView.image = [UIImage imageNamed:@"ibooks-icon.png"];
}
else if ([[selectednavItem.document.fileName pathExtension] isEqualToString:@"png"] || [[selectednavItem.document.fileName pathExtension] isEqualToString:@"bmp"] || [[selectednavItem.document.fileName pathExtension] isEqualToString:@"jpg"] || [[selectednavItem.document.fileName pathExtension] isEqualToString:@"jpeg"] || [[selectednavItem.document.fileName pathExtension] isEqualToString:@"tif"] || [[selectednavItem.document.fileName pathExtension] isEqualToString:@"tiff"] || [[selectednavItem.document.fileName pathExtension] isEqualToString:@"gif"])
{
cell.imageView.image = [UIImage imageNamed:@"41-picture-frame.png"];
}
else
{
cell.imageView.image = [UIImage imageNamed:@"179-notepad.png"];
}
}
else if (selectednavItem.attachment != nil) {
cell.detailTextLabel.text = [[selectednavItem.attachment valueForKey:@"itemDescription"] description];
if ([[selectednavItem.attachment.fileName pathExtension] isEqualToString:@"pdf"])
{
cell.imageView.image = [UIImage imageNamed:@"pdf.png"];
}
else if ([[selectednavItem.attachment.fileName pathExtension] isEqualToString:@"doc"] || [[selectednavItem.attachment.fileName pathExtension] isEqualToString:@"docx"])
{
cell.imageView.image = [UIImage imageNamed:@"Word-32x32.png"];
}
else if ([[selectednavItem.attachment.fileName pathExtension] isEqualToString:@"xls"] || [[selectednavItem.attachment.fileName pathExtension] isEqualToString:@"xlsx"])
{
cell.imageView.image = [UIImage imageNamed:@"Excel-32x32.png"];
}
else if ([[selectednavItem.attachment.fileName pathExtension] isEqualToString:@"ppt"] || [[selectednavItem.attachment.fileName pathExtension] isEqualToString:@"pps"])
{
cell.imageView.image = [UIImage imageNamed:@"Powerpoint-32x32.png"];
}
else if ([[selectednavItem.attachment.fileName pathExtension] isEqualToString:@"mp3"])
{
cell.imageView.image = [UIImage imageNamed:@"65-note.png"];
}
else if ([[selectednavItem.attachment.fileName pathExtension] isEqualToString:@"mp4"])
{
cell.imageView.image = [UIImage imageNamed:@"46-movie-2.png"];
}
else if ([[selectednavItem.document.fileName pathExtension] isEqualToString:@"ibooks"])
{
cell.imageView.image = [UIImage imageNamed:@"ibooks-icon.png"];
}
else if ([[selectednavItem.attachment.fileName pathExtension] isEqualToString:@"png"] || [[selectednavItem.attachment.fileName pathExtension] isEqualToString:@"bmp"] || [[selectednavItem.attachment.fileName pathExtension] isEqualToString:@"jpg"] || [[selectednavItem.attachment.fileName pathExtension] isEqualToString:@"jpeg"] || [[selectednavItem.attachment.fileName pathExtension] isEqualToString:@"tif"] || [[selectednavItem.attachment.fileName pathExtension] isEqualToString:@"tiff"] || [[selectednavItem.attachment.fileName pathExtension] isEqualToString:@"gif"])
{
cell.imageView.image = [UIImage imageNamed:@"41-picture-frame.png"];
}
else
{
cell.imageView.image = [UIImage imageNamed:@"179-notepad.png"];
}
}
}
解决方法
原文地址：https://www.jb51.cc/iOS/328910.html
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