在我的应用中，我使用Parse。我把它设置成这样：
- (id)initWithCoder:(NSCoder *)aDecoder
{
self = [super initWithCoder:aDecoder];
if (self) {
// The className to query on
self.parseClassName = @"Prayers";
// Whether the built-in pull-to-refresh is enabled
self.pullToRefreshEnabled = YES;
// Whether the built-in pagination is enabled
self.paginationEnabled = YES;
// The number of objects to show per page
self.objectsPerPage = 20;
}
return self;
}
- (PFQuery *)queryForTable {
PFQuery *query = [PFQuery queryWithClassName:@"Prayers"];
// If no objects are loaded in memory, we look to the cache first to fill the table
// and then subsequently do a query against the network.
if (self.objects.count == 0) {
query.cachePolicy = kPFCachePolicyCacheThenNetwork;
}
[query orderByDescending:@"createdAt"];
return query;
}
- (UITableViewCell *)tableView:(UITableView *)tableView
cellForRowAtIndexPath:(NSIndexPath *)indexPath
object:(PFObject *)object
{
static NSString *CellIdentifier = @"Cell";
Cell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if (cell == nil) {
cell = [[Cell alloc] initWithStyle:UITableViewCellStyleSubtitle reuseIdentifier:CellIdentifier];
}
self.theObject = object;
BOOL anony = [object[@"Anonymous"] boolValue];
if (!anony) {
NSString *names = [[object[@"FirstName"] stringByAppendingString:@" "] stringByAppendingString:object[@"LastName"]];
cell.profileName.text = names;
cell.contentLabel.text = object[@"Request"];
cell.firstName = object[@"FirstName"];
cell.lastName = object[@"LastName"];
cell.iostoken = object[@"DeviceID"];
cell.request = names;
cell.prayerObject = object;
PFFile *thumbnail = object[@"ProfilePic"];
cell.profilePic.image = [UIImage imageNamed:@"AppIcon60x60@2x.png"];
/*[cell.commentButton addTarget:self action:@selector(didTapCommentButtonAction:) forControlEvents:UIControlEventTouchUpInside];
[cell.commentButton setTitle:@"Share" forState:UIControlStateNormal];
[cell.commentButton setTitleColor:[UIColor blackColor] forState:UIControlStateNormal];
[cell.commentButton setTitleColor:[UIColor greenColor] forState:UIControlStateHighlighted];*/
[thumbnail getDataInBackgroundWithBlock:^(NSData *imageData, NSError *error) {
UIImage *thumbnailImage = [UIImage imageWithData:imageData];
UIImageView *thumbnailImageView = [[UIImageView alloc] initWithImage:thumbnailImage];
cell.profilePic.image = thumbnailImage;
}];
NSString *dates = object[@"dateMade"];
NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
[formatter setDateFormat:@"MMM_dd_yyyy"];
NSDate *datefromstring = [formatter dateFromString:dates];
NSDateFormatter *formatter2 = [[NSDateFormatter alloc] init];
[formatter2 setDateFormat:@"MMM dd, yyyy"];
cell.dateLabel.text = [formatter2 stringFromDate:datefromstring];
UIFont *cellFont = [UIFont fontWithName:@"Verdana-Bold" size:15];
UIFont *cellFont2 = [UIFont fontWithName:@"Verdana-Bold" size:12];
}
else {
// Configure the cell to show todo item with a priority at the bottom
cell.profileName.text = object[@"Title"];
cell.contentLabel.text = object[@"Request"];
cell.firstName = object[@"FirstName"];
cell.lastName = object[@"LastName"];
cell.iostoken = object[@"DeviceID"];
cell.request = object[@"Title"];
cell.prayerObject = object;
PFFile *thumbnail = object[@"ProfilePic"];
cell.profilePic.image = [UIImage imageNamed:@"AppIcon60x60@2x.png"];
[thumbnail getDataInBackgroundWithBlock:^(NSData *imageData, NSError *error) {
UIImage *thumbnailImage = [UIImage imageWithData:imageData];
UIImageView *thumbnailImageView = [[UIImageView alloc] initWithImage:thumbnailImage];
cell.profilePic.image = thumbnailImage;
}];
NSString *dates = object[@"dateMade"];
NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
[formatter setDateFormat:@"MMM_dd_yyyy"];
NSDate *datefromstring = [formatter dateFromString:dates];
NSDateFormatter *formatter2 = [[NSDateFormatter alloc] init];
[formatter2 setDateFormat:@"MMM dd, yyyy"];
cell.dateLabel.text = [formatter2 stringFromDate:datefromstring];
}
return cell;
}
- (CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath {
PFObject *entry = [self.objects objectAtIndex:indexPath.row];
NSString *commentString = entry[@"Request"];
NSString *nameString = @"";
NSLog(@"%@", commentString);
return [Cell heightForCellWithContentString:(NSString *)commentString] +25 ;
}
#pragma mark -
#pragma mark Table view delegate
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath {
#if __IPHONE_OS_VERSION_MAX_ALLOWED >= 30200
if( UI_USER_INTERFACE_IDIOM() == UIUserInterfaceIdiomPad )
{
if (_webViewController2 == nil) {
self.webViewController2 = [[[WebViewController2 alloc] initWithNibName:@"WebViewController2" bundle:[NSBundle mainBundle]] autorelease];
}
RSSEntry *entry = [_allEntries objectAtIndex:indexPath.row];
_webViewController2.entry = entry;
[self.navigationController pushViewController:_webViewController2 animated:YES];
[self.objects objectAtIndex:indexPath.row];
}
else {
PFObject *entry = [self.objects objectAtIndex:indexPath.row];
if (_webViewController == nil) {
self.webViewController = [[[WebViewController alloc] initWithNibName:@"WebViewController" bundle:[NSBundle mainBundle]] autorelease];
}
_webViewController.finalObject = entry;
[self.navigationController pushViewController:_webViewController animated:YES];
}
#endif
}
根据我的理解，这应该一次加载20个项目，当你滚动到那些项目的结尾时，加载下一个20.但是，一旦我有20个项目，应用程序崩溃，我收到此消息：
Terminating app due to uncaught exception 'NSRangeException', reason: '*** -[__NSArrayM objectAtIndex:]: index 20 beyond bounds [0 .. 19]'
在放入异常断点后，导致错误的行在heightForRow方法
PFObject *entry = [self.objects objectAtIndex:indexPath.row];
发生了什么事？