Nothing shows in custom headerView - ios

Question

When I run the application, the header view container space is there, and is visible. I'm trying to display the username inside the header view, but nothing is showing up. Here is my code so far in the tableView:
#import "HomeView.h"
#interface HomeView () <UIActionSheetDelegate, UIImagePickerControllerDelegate>
#end
#implementation HomeView
- (void)viewDidLoad {
[super viewDidLoad];
if ([PFUser currentUser]) {
NSLog(#"Welcome to the App, %#", [self.user objectForKey:#"username"]);
} else {
LoginView *loginView = [[LoginView alloc] init];
[loginView setHidesBottomBarWhenPushed:YES];
[loginView.navigationItem setHidesBackButton:YES];
[self.navigationController pushViewController:loginView animated:NO];
}
UIBarButtonItem *takePhoto = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemCamera target:self action:#selector(takePhoto:)];
self.navigationItem.rightBarButtonItem = takePhoto;
// [self.tableView registerClass:[HomeViewCell class] forCellReuseIdentifier:#"cellIdentifier"];
// [self.tableView registerNib:[UINib nibWithNibName:#"HomeViewCell" bundle:nil]
// forCellReuseIdentifier:#"cellIdentifier"];
self.tableView.delegate = self;
self.tableView.dataSource = self;
}
- (id)initWithStyle:(UITableViewStyle)style {
self = [super initWithStyle:style];
if (self) {
self.reusableSectionHeaderViews = [NSMutableSet setWithCapacity:3];
}
return self;
}
- (void)viewWillAppear:(BOOL)animated {
[super viewWillAppear:animated];
PFQuery *query = [PFQuery queryWithClassName:#"UserPhotos"];
[query orderByDescending:#"createdAt"];
[query findObjectsInBackgroundWithBlock:^(NSArray *objects, NSError *error) {
if (error) {
NSLog(#"Error: %# %#", error, [error userInfo]);
} else {
self.userPhotos = objects;
NSLog(#"Retrieved objects: %#", self.userPhotos);
[self.tableView reloadData];
}
}];
}
#pragma mark - Table view data source
- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView {
NSInteger sections = self.userPhotos.count;
// Return the number of sections.
return sections;
}
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
// Return the number of rows in the section.
return 1;
}
-(UIView *)tableView:(UITableView *)tableView viewForHeaderInSection:(NSInteger)section {
if (section == self.userPhotos.count) {
// Load More section
return nil;
}
HomeHeaderView *headerView = [self dequeueReusableSectionHeaderView];
if (!headerView) {
headerView = [[HomeHeaderView alloc] initWithFrame:CGRectMake( 0.0f, 0.0f, self.view.bounds.size.width, 44.0f) buttons:HomePhotoHeaderButtonsDefault];
headerView.delegate = self;
[self.reusableSectionHeaderViews addObject:headerView];
}
//Setting the username display.
PFObject *owner = [self.userPhotos objectAtIndex:section];
PFUser *user = [owner objectForKey:#"user"];
[user fetchIfNeededInBackgroundWithBlock:^(PFObject *object, NSError *error) {
if (!error) {
NSString *username = user.username;
[headerView.userButton setTitle:username forState:UIControlStateNormal];
}
}];
return headerView;
}
- (HomeHeaderView *)dequeueReusableSectionHeaderView {
for (HomeHeaderView *sectionHeaderView in self.reusableSectionHeaderViews) {
if (!sectionHeaderView.superview) {
// we found a section header that is no longer visible
return sectionHeaderView;
}
}
return nil;
}
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
static NSString *CellIdentifier = #"cellIdentifier";
HomeViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if(cell == nil)
{
cell = [[HomeViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier];
}
//Setting the image in the cell.
PFObject *carPhoto = [self.userPhotos objectAtIndex:indexPath.row];
PFFile *imageFile = [carPhoto objectForKey:#"imageFile"];
NSURL *imageFileUrl = [[NSURL alloc] initWithString:imageFile.url];
NSData *imageData = [NSData dataWithContentsOfURL:imageFileUrl];
cell.carImage.contentMode = UIViewContentModeScaleAspectFit;
cell.carImage.image = [UIImage imageWithData:imageData];
return cell;
}
- (CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath
{
return 269;
}
- (CGFloat)tableView:(UITableView *)tableView heightForHeaderInSection:(NSInteger)section {
if (section == self.userPhotos.count) {
return 0.0f;
}
return 44.0f;
}

Answer 1

[user fetchIfNeededInBackgroundWithBlock:^(PFObject *object, NSError *error) {
if (!error) {
NSString *username = user.username;
[headerView.userButton setTitle:username forState:UIControlStateNormal];
}
}];
The code above, you are updating the headerview UI from a background thread. You need to wrap the UI part so it performs on the main thread.
dispatch_async(dispatch_get_main_queue(), ^{
[headerView.userButton setTitle:username forState:UIControlStateNormal];
};
You need to be careful though, you are performing a background operation and then updating the header which you are reusing. There is a chance that the header is reused for a new section before the operation finishes and it is then set with the wrong username for that section. You can take care of this by not reusing the header or canceling the network operation if the header scrolls off screen before the operation finishes.