iOS - Cell不允许在UITableView中进行选择

Question

我有一个UITableViewCell的子类，我在其中添加了4个UILabel和一个PFImageView（app与后端服务的Parse通信）。这是我的子类代码。

DiscoverTableViewCell.h

#import <UIKit/UIKit.h>

@interface DiscoverTableViewCell : UITableViewCell

@property (strong, nonatomic) PFImageView *profilePictureImageView;

@property (strong, nonatomic) UILabel *nameLabel;
@property (strong, nonatomic) UILabel *usernameLabel;

@property (strong, nonatomic) UILabel *descriptionLabel;
@property (strong, nonatomic) UILabel *numberOfFollowersLabel;

@end

DiscoverTableViewCell.m

#import "DiscoverTableViewCell.h"

@implementation DiscoverTableViewCell

- (id)initWithStyle:(UITableViewCellStyle)style reuseIdentifier:(NSString *)reuseIdentifier
{
    self = [super initWithStyle:style reuseIdentifier:reuseIdentifier];
    if (self) {
        // Initialization code
        self.profilePictureImageView = [[PFImageView alloc] initWithFrame:CGRectMake(15, 10, 55, 55)];
        self.nameLabel = [[UILabel alloc] initWithFrame:CGRectMake(80, 5, 220, 20)];
        self.usernameLabel = [[UILabel alloc] initWithFrame:CGRectMake(80, 25, 220, 14)];
        self.numberOfFollowersLabel = [[UILabel alloc] initWithFrame:CGRectMake(80, 40, 220, 14)];
        self.descriptionLabel = [[UILabel alloc] initWithFrame:CGRectMake(80, 58, 220, 20)];

        self.nameLabel.font = [UIFont systemFontOfSize:15];

        self.usernameLabel.font = [UIFont systemFontOfSize:12];
        self.usernameLabel.textColor = [UIColor lightGrayColor];

        self.descriptionLabel.font = [UIFont systemFontOfSize:12];
        self.numberOfFollowersLabel.font = [UIFont systemFontOfSize:12];

        self.descriptionLabel.textColor = [UIColor lightGrayColor];
        self.numberOfFollowersLabel.textColor = [UIColor lightGrayColor];

        self.profilePictureImageView.userInteractionEnabled = YES;
        self.nameLabel.userInteractionEnabled = YES;
        self.usernameLabel.userInteractionEnabled = YES;
        self.descriptionLabel.userInteractionEnabled = YES;
        self.numberOfFollowersLabel.userInteractionEnabled = YES;

        self.userInteractionEnabled = YES;

        [self.contentView addSubview:self.profilePictureImageView];
        [self.contentView addSubview:self.nameLabel];
        [self.contentView addSubview:self.usernameLabel];
        [self.contentView addSubview:self.descriptionLabel];
        [self.contentView addSubview:self.numberOfFollowersLabel];
    }
    return self;
}

- (void)awakeFromNib
{
    // Initialization code
}

- (void)setSelected:(BOOL)selected animated:(BOOL)animated
{
    [super setSelected:selected animated:animated];
    // Configure the view for the selected state
}

@end

这是我对tableView的实现：cellForRowAtIndexPath：method。

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath     *)indexPath
{
    static NSString *identifier = @"discoverCell";
    DiscoverTableViewCell *cell = (DiscoverTableViewCell *)[tableView dequeueReusableCellWithIdentifier:identifier];
    if (!cell){
        cell = [[DiscoverTableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:identifier];
    }

    if ([tableView isEqual:self.searchDisplayController.searchResultsTableView]){

        if (self.searchResults.count > 0){
            if (self.searchScopeIndex == 0){
                //Display users
                PFUser *user = (PFUser *)[self.searchResults objectAtIndex:indexPath.row];
                cell.textLabel.text = [user objectForKey:@"name"];
                cell.detailTextLabel.text = [NSString stringWithFormat:@"@%@", [user objectForKey:@"username"]];
            } else if (self.searchScopeIndex == 1){
                //Display hashtags


            }
        }
    } else {
        PFUser *user = (PFUser *)[self.objects objectAtIndex:indexPath.row];
        NSString *name = [user objectForKey:@"name"];
        NSString *username = [user objectForKey:@"username"];
        NSString *description = [user objectForKey:@"description"];
        NSNumber *numberOfFollowers = [user objectForKey:@"followerCount"];
        PFFile *profilePicture = [user objectForKey:@"profilePicture"];
        cell.profilePictureImageView.file = profilePicture;
        [cell.profilePictureImageView loadInBackground];
        cell.nameLabel.text = name;
        cell.usernameLabel.text = [NSString stringWithFormat:@"@%@", username];
        if (![description isEqualToString:@""] && ![description isEqualToString:@"(null)"]){
            cell.descriptionLabel.text = description;
        }
        if ([numberOfFollowers integerValue] == 1){
            cell.numberOfFollowersLabel.text = [NSString stringWithFormat:@"%@ follower", numberOfFollowers];
        } else {
            cell.numberOfFollowersLabel.text = [NSString stringWithFormat:@"%@ followers", numberOfFollowers];
        }
        cell.accessoryType = UITableViewCellAccessoryDisclosureIndicator;
        cell.selectionStyle = UITableViewCellSelectionStyleDefault;
    }
    return cell;
}

问题是，在iOS设备上运行时，这不允许选择单元格。单元格显示所有信息OK，但从不调用方法tableView：didSelectRowAtIndexPath :. 谢谢。