Friday, June 7, 2013

UITableViewCell accessoryView example in Objective C (iOS).

UITableViewCell accessoryView

A view that is used, typically as a control, on the right side of the cell (normal state).

@property(nonatomic, retain) UIView *accessoryView

Discussion of [UITableViewCell accessoryView]
If the value of this property is not nil, the UITableViewCell class uses the given view for the accessory view in the table view’s normal (default) state; it ignores the value of the accessoryType property. The provided accessory view can be a framework-provided control or label or a custom view. The accessory view appears in the right side of the cell.

The accessory view cross-fades between normal and editing states if it set for both states; use the editingAccessoryView property to set the accessory view for the cell during editing mode. If this property is not set for both states, the cell is animated to slide in or out, as necessary.

UITableViewCell accessoryView example.
UIImage *image = (checked) ? [UIImage imageNamed:@"checked.png"] : [UIImage imageNamed:@"unchecked.png"];

UIButton *button = [UIButton buttonWithType:UIButtonTypeCustom];
CGRect frame = CGRectMake(0.0, 0.0, image.size.width, image.size.height);
button.frame = frame;
[button setBackgroundImage:image forState:UIControlStateNormal];

[button addTarget:self action:@selector(checkButtonTapped:event:)  forControlEvents:UIControlEventTouchUpInside];
button.backgroundColor = [UIColor clearColor];
cell.accessoryView = button;

Example of [UITableViewCell accessoryView].
- (id)initForIdentifier:(NSString *)reuseIdentifier;
    // the subclass specifies style itself
    self = [super initWithStyle:UITableViewCellStyleValue1 reuseIdentifier:reuseIdentifier];
    if (self) {
        // get the button elsewhere
        UIButton *accBtn = [ViewFactory createTableViewCellDisclosureButton];
        [accBtn addTarget: self
                   action: @selector(accessoryButtonTapped:withEvent:)
         forControlEvents: UIControlEventTouchUpInside];
        self.accessoryView = accBtn;
    return self;

UITableViewCell accessoryView example.
Define a macro for tags of buttons:

#define AccessoryViewTagSinceValue 100000 // (AccessoryViewTagSinceValue * sections + rows) must be LE NSIntegerMax
Create button and set the cell.accessoryView when creating a cell

UIButton *accessoryButton = [UIButton buttonWithType:UIButtonTypeContactAdd];
accessoryButton.frame = CGRectMake(0, 0, 30, 30);
[accessoryButton addTarget:self action:@selector(accessoryButtonTapped:) forControlEvents:UIControlEventTouchUpInside];
cell.accessoryView = accessoryButton;
Set cell.accessoryView.tag by indexPath in UITableViewDataSource method -tableView:cellForRowAtIndexPath:

cell.accessoryView.tag = indexPath.section * AccessoryViewTagSinceValue + indexPath.row;
Event handler for buttons

- (void) accessoryButtonTapped:(UIButton *)button {
    NSIndexPath *indexPath = [NSIndexPath indexPathForRow:button.tag % AccessoryViewTagSinceValue
                                                inSection:button.tag / AccessoryViewTagSinceValue];

    [self.tableView.delegate tableView:self.tableView accessoryButtonTappedForRowWithIndexPath:indexPath];
Implement the UITableViewDelegate method

- (void)tableView:(UITableView *)tableView accessoryButtonTappedForRowWithIndexPath:(NSIndexPath *)indexPath {
    // do sth.

End of UITableViewCell accessoryView example article.