Initial frame to use for UITableViewCell's bac

问题:

I'm currently initializing my UITableViewCell's backgroundView's frame with self.frame. This seems to work fine for device orientation changes (cell background fills entire cell, looks fine etc). What's a better frame to use (if any)?

Edit #1: I've also initialized the backgroundView with CGRectZero as the frame. This seems to make no difference (UITableViewCells and backgroundViews function just fine in all interface orientations).

I've also tested setting the autoresizingMask property of the backgroundView. This made no difference either. I'd just like to understand what (if anything) is affected by the backgroundViews initial frame.

回答1:

Assuming that you are trying to add a UIImageView as backgroundView and that you are trying to resize that imageView, here's my experience:

It seems to be impossible to change the frame of UITableViewCell.backgroundView (or at least not a thing Apple recommends, hence it's not mentioned in the documentation). To use a custom sized UIImageView, eg with a resizable UIImage, as background in a UITableViewCell, I do the following:

1) Create a UIImageView and set its image property to an image of your wish.

2) Add the UIImageView as a subview of the UITableViewCell using the addSubview: message.

3) Send the UIImageView to the back using sendSubviewToBack: message.

This puts your UIImageView behind any other added subviews and you are now able to manipulate the frame of your 'backgroundView' (aka the imageview).

To make sure the imageview will fit the tableViewCell's frame, use cell.frame's height and width properties when calculating the height of your imageview.

回答2:

If you develop custom table view cell the solution is to adjust the frame in layoutSubviews method. Here is custom UITableViewCell from one of my projects, I needed 10 points margin from left:

#import "TETopicCell.h"
#import "UIColor+Utils.h"

@implementation TETopicCell

@synthesize topicTitleLabel = _topicTitleLabel;

- (id)initWithStyle:(UITableViewCellStyle)style reuseIdentifier:(NSString *)reuseIdentifier
{
    self = [super initWithStyle:style reuseIdentifier:reuseIdentifier];
    if (self) {

        UIImageView *bgImageView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"theme_btn_yellow"]];
        bgImageView.contentMode = UIViewContentModeTopLeft;
        bgImageView.frame = CGRectMake(0.0f, 0.0f, 239.0f, 42.0f);
        self.backgroundView = bgImageView;

        _topicTitleLabel = [[UILabel alloc] initWithFrame:CGRectMake(46.0f, 0.0f, 206.0f, 42.0f)];
        _topicTitleLabel.backgroundColor = [UIColor clearColor];
        _topicTitleLabel.textColor = [UIColor colorWithR:116 G:74 B:1];

        [self.contentView addSubview:_topicTitleLabel];
    }
    return self;
}

- (void)layoutSubviews
{
    [super layoutSubviews];

    // update frame here
    self.backgroundView.frame = CGRectOffset(self.backgroundView.frame, 10.0f, 0.0f);

    // and here      
    if (self.selectedBackgroundView){
        self.selectedBackgroundView.frame = CGRectOffset(self.selectedBackgroundView.frame, 10.0f, 0.0f);
    }
}

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

    if (selected) {
        UIImageView *selectedImageView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"theme_btn_red"]];
        selectedImageView.contentMode = UIViewContentModeTopLeft;
        selectedImageView.frame = CGRectMake(0.0f, 0.0f, 239.0f, 42.0f);

        self.selectedBackgroundView = selectedImageView;
        [_topicTitleLabel setTextColor:[UIColor colorWithR:255 G:211 B:211]];
    }
    else {
        self.selectedBackgroundView = nil;
        [_topicTitleLabel setTextColor:[UIColor colorWithR:116 G:74 B:1]];
    }
}

@end