Unable to get UIImage size height after AFNetworking

Question

I have been trying to follow this SO thread but to no avail. The problem I get is that the image does not show which I assume is because the height is null when i set the heightForRowAtIndexPath to return image.size.height.

Feed.h

#import "AFNetworking.h"
#import <UIKit/UIKit.h>

@interface Feed : UITableViewController

@end

Feed.m

#import "Feed.h"
#import "NSDictionary+Feed.h"
#import "NSDictionary+Feed_package.h"
#import "UIImageView+AFNetworking.h"
#import "FeedItem.h"

@interface Feed ()

@property(strong) NSDictionary *json_from_url;
@property(strong) NSMutableDictionary *ImageHeightDic;

@end

static NSString * const BaseURLString = @"https://xxxx";

@implementation Feed

- (void)viewDidLoad {
    [super viewDidLoad];

    self.randomSelection = [[NSMutableDictionary alloc] init];

    NSURL *url = [NSURL URLWithString:BaseURLString];
    NSURLRequest *request = [NSURLRequest requestWithURL:url];

    AFHTTPRequestOperation *operation = [[AFHTTPRequestOperation alloc] initWithRequest:request];
    operation.responseSerializer = [AFJSONResponseSerializer serializer];

    [operation setCompletionBlockWithSuccess:^(AFHTTPRequestOperation *operation, id responseObject) {

        self.json_from_url = (NSDictionary *)responseObject;
        [self.tableView reloadData];

    } failure:^(AFHTTPRequestOperation *operation, NSError *error) {
        UIAlertView *alertView = [[UIAlertView alloc] initWithTitle:@"Error Retrieving Weather"
                                                            message:[error localizedDescription]
                                                           delegate:nil
                                                  cancelButtonTitle:@"Ok"
                                                  otherButtonTitles:nil];
        [alertView show];
    }];

    [operation start];

}

- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];

}

- (void)viewDidAppear:(BOOL)animated {
    [super viewDidAppear:animated];

}

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section{
    NSArray *feed_array = [self.json_from_url feed_array];
    return [feed_array count];
}


- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath{

    FeedItem *feedcell = [tableView dequeueReusableCellWithIdentifier:@"FeedItemCell"];

    if(!feedcell){

        [tableView registerNib:[UINib nibWithNibName:@"FeedItem" bundle:nil] forCellReuseIdentifier:@"FeedItemCell"];

        feedcell = [tableView dequeueReusableCellWithIdentifier:@"FeedItemCell"];

    }

    NSDictionary *daysWeather = nil;

    NSArray *feed_array = [self.json_from_url feed_array];

    daysWeather = feed_array[indexPath.row];

    feedcell.captionLabel.text = [daysWeather feed_caption];
    NSURLRequest *request = [NSURLRequest requestWithURL:[NSURL URLWithString:[daysWeather image_url]]

                                             cachePolicy:NSURLRequestReturnCacheDataElseLoad

                                         timeoutInterval:60];

    UIImage *placeholderImage = [UIImage imageNamed:@"feed_image_loading"];
    [feedcell.imageLabel setImageWithURLRequest:request
                               placeholderImage:placeholderImage success:^(NSURLRequest *request, NSHTTPURLResponse *response, UIImage *image) {

        feedcell.imageLabel.image = image;                          
        [self.ImageHeightDic setObject:image forKey:[NSString stringWithFormat:@"%li,%li",(long)indexPath.row,(long)indexPath.section]];
                               } failure:nil];

        [tableView reloadRowsAtIndexPaths:[NSArray arrayWithObjects:indexPath, nil] withRowAnimation:YES];
        [feedcell setNeedsLayout];

    return feedcell;

}


-(CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath
{

    UIImage *image = (UIImage *)[self.ImageHeightDic objectForKey:
                                 [NSString stringWithFormat:@"%li,%li",
                                  (long)indexPath.row,(long)indexPath.section]];

    return image.size.height;
    // Here is where i think the problem is because it works 
    // when i comment out the above and uncomment below

    //return 40;

}



@end

Sulthan · Accepted Answer · 2015-08-30T23:09:35.513

[tableView reloadRowsAtIndexPaths:@[indexPath]
                 withRowAnimation:YES];

must be called from the request success block. You are calling it before you actually get the image. That means your cell size won't get updated. Since you actually just want to reload the heights, you can use the following from the success block:

dispatch_async(dispatch_get_main_queue(), ^(void){
   [tableView beginUpdates];
   [tableView endUpdates];
});

That will update the heights but it won't perform a full reload of the cell. (dispatch_async used to perform the operation on the main thread).

However, you should also cover the case when the image is not loaded yet and return a valid cell height, otherwise your placeholder won't be displayed.

Unable to get UIImage size height after AFNetworking

1 Answers1