Question

我正在使用PFQueryTableViewController，它需要在调用QueryForTableView之前将某个PFUser传递给它。为了解决这个问题，我在PFQueryTableViewController中创建了一个协议，它有一个名为userForProfileTableView的必需方法。

@protocol profileTableViewDataSource <NSObject>

@required

-(PFUser *)userForProfileTableView;

@end

上一个视图控制器使用此方法设置PFUser。但是，以前的视图控制器仅将自身设置为prepareForSegue：sender：completion中的dataSource。调用此方法时，已调用queryForTableView和initWithCoder方法，这意味着PFQueryTableViewClass没有PFObject可供使用。

如何在初始化后直接获得对PFQueryTableViewController的引用，或者在调用queryForTableView之前是否可以通过另一种方式传递PFUser？任何帮助/想法将非常感激。

提前致谢！

代码：

两者都是PFQueryTableViewController的子类

第一个视图控制器，它是数据源：

.h（不重要）

的.m

#import "FeedQueryTableViewController.h"
#import "FeedTableViewCell.h"

@interface FeedQueryTableViewController ()

@end

@implementation FeedQueryTableViewController{
    PFUser * userToPass;
}

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view.
}

- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

- (instancetype)initWithCoder:(NSCoder *)coder
{
    self = [super initWithCoder:coder];
    if (self) {
        self.parseClassName = @"Question";
    }
    return self;
}

-(PFQuery *)queryForTable{
    //First query for followed users
    PFQuery * query = [PFQuery queryWithClassName:@"Activity"];
    [query whereKey:@"fromUser" equalTo:[PFUser currentUser]];
    [query whereKey:@"type" equalTo:@"follow"];
    [query includeKey:@"toUser"];
    [query includeKey:@"fromUser"];

    //Second query for questions
    PFQuery * questionQuery = [PFQuery queryWithClassName:@"Question"];
    [questionQuery whereKey:@"User" matchesKey:@"toUser" inQuery:query];
    [questionQuery includeKey:@"User"];

    return questionQuery;
}

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

    FeedTableViewCell * cell = [tableView dequeueReusableCellWithIdentifier:@"cell"];
    if (cell == nil) {
        cell = [[FeedTableViewCell alloc]initWithStyle:UITableViewCellStyleDefault reuseIdentifier:@"cell"];
    }

    //Set values of cell

    [cell.usernameButton setTitle:[[object objectForKey:@"User"]username] forState:UIControlStateNormal];
    [cell.usernameButton addTarget:self action:@selector(userButtonPressed:) forControlEvents:UIControlEventTouchUpInside];
    cell.usernameButton.tag = indexPath.row;
    cell.questionTextView.text = [object objectForKey:@"Question"];

    return cell;
}

-(PFUser *)userForProfileTableView{

    //This happens before the other class

    if (userToPass != nil){
        NSLog(@"%@", userToPass.username);
        return userToPass;}
    else{
        return userToPass;
}
}

-(void)userButtonPressed:(UIButton *)sender {
    //Type checking is sketchy here and could lead to potential crashes
    PFObject * object = [[[self queryForTable]findObjects] objectAtIndex:sender.tag];
    userToPass = [object objectForKey:@"User"];
    [self performSegueWithIdentifier:@"userProfile" sender:self];
}

-(void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender{
    ProfileTableViewController * ptvc = segue.destinationViewController;
    ptvc.dataSource = self;
}

@end

View Controller包含协议，并且正在检索PFUser以基于Tableview数据

·H

//
//  ProfileTableViewController.h
//  qSocialNetwork
//
//  Created by Sam Kirkiles on 7/29/14.
//  Copyright (c) 2014 Sam Kirkiles. All rights reserved.
//

#import <Parse/Parse.h>

@protocol profileTableViewDataSource <NSObject>

@required

-(PFUser *)userForProfileTableView;

@end

@interface ProfileTableViewController : PFQueryTableViewController

@property (weak, nonatomic) IBOutlet UILabel *profileNameLabel;
@property (strong, nonatomic) PFUser * userToDisplay;

@property (weak) id <profileTableViewDataSource> dataSource;

@end

的.m

//
//  ProfileTableViewController.m
//  qSocialNetwork
//
//  Created by Sam Kirkiles on 7/29/14.
//  Copyright (c) 2014 Sam Kirkiles. All rights reserved.
//

#import "ProfileTableViewController.h"

@interface ProfileTableViewController ()

@end

@implementation ProfileTableViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view.
    [self.dataSource userForProfileTableView];
}

- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

- (id)initWithCoder:(NSCoder *)aCoder
{
    self = [super initWithCoder:aCoder];
    if (self) {
        self.parseClassName = @"Activity";
    }
    return self;
}

-(void)objectsWillLoad{
    [super objectsWillLoad];
    self.userToDisplay = [self.dataSource userForProfileTableView];
    if (self.userToDisplay != nil) {
        NSLog(@"sdfsfd");
        [self queryForTable];
        //A user has been passed to this view controller
    }else{
        //User the current user as a backup
        //This feature will be added later

    }

}

-(PFQuery *)queryForTable{
    if (self.userToDisplay != nil){
    PFQuery * query = [PFQuery queryWithClassName:@"Question"];
    [query whereKey:@"User" equalTo:self.userToDisplay];
        return query;
    }
    PFQuery *noUserQuery = [PFQuery queryWithClassName:@"Question"];
    return noUserQuery;
}

-(UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath object:(PFObject *)object{
    UITableViewCell * cell = [tableView dequeueReusableCellWithIdentifier:@"cell"];
    if (cell == nil){
        cell = [[UITableViewCell alloc]initWithStyle:UITableViewCellStyleDefault reuseIdentifier:@"cell"];
    }
    cell.textLabel.text = [object objectForKey:@"Question"];

    return cell;
}

/*
#pragma mark - Navigation

// In a storyboard-based application, you will often want to do a little preparation before navigation
- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender {
    // Get the new view controller using [segue destinationViewController].
    // Pass the selected object to the new view controller.
}
*/

@end

Answer 1

尝试在前一个视图控制器上为queryForTable方法设置对象时遇到了类似的问题。我想出的解决方案是创建一个自定义初始化程序，设置对象，然后调用超级初始化程序。 e.g。

- (id)initWithParent:(PFObject *)parent
{
    self.parent = parent;
    self = [self initWithStyle:UITableViewStylePlain];
    if (self) {
       ...
    }
    return self;
}

我知道这不是一个优雅的解决方案，但这是我可以让queryForTable方法使用我的对象进行查询而不必在viewDidAppear中重新运行查询的唯一方法。

在View Controller初始化之后设置委托，创建Parse方法QueryForTableView的问题

1 个答案: