我有一个消息视图，用户可以在其中查看对话并输入＆amp;发信息。用户长按消息时显示菜单（上下文菜单的种类）。我已经分别使用TableView和Button进行聊天记录和发送消息按钮。 我的问题是canPerformAction：当我点击Button或TableView时，会触发withSender方法。此外，这段代码在iOS 9.0下工作正常。
@interface MessageDetailViewController ()
- (void)updateDetailView;
- (void)setMessageBar;
- (void)setCallButton;
@end
@implementation MessageDetailViewController
{
}
@synthesize messageField;
@synthesize messageList;
@synthesize messageBarView;
@synthesize navigationBarView;
- (void)viewDidLoad
{
[super viewDidLoad];
NSLog(@"MessageDetailView: viewDidLoad method called.");
// Observe keyboard hide and show notifications to resize the text view appropriately.
[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyboardWillShow:) name:UIKeyboardWillShowNotification object:nil];
[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyboardWillHide:) name:UIKeyboardWillHideNotification object:nil];
[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(didHideEditMenu:) name:UIMenuControllerDidHideMenuNotification object:nil];
[messageField becomeFirstResponder];
messageArray = [[NSMutableArray alloc] init];
typingImage = [[UIImageView alloc] init];
presenceImage = [[UIImageView alloc] init];
navigationBarView = [[UIView alloc] init];
viewHeight = self.view.frame.size.height;
}
- (void)viewWillAppear:(BOOL)animated
{
[super viewWillAppear:YES];
[messageField setDelegate:self];
messageList.delegate = self;
messageList.dataSource = self;
[self updateDetailView];
[messageList reloadData];
}
- (BOOL)canBecomeFirstResponder
{
return YES;
}
/**
* This method is called to send instance method to server.
*/
- (void)onSendMessageButtonPressed:(id)sender
{
if([messageField.text length] == 0)
{
return;
}
messageField.text = [messageField.text substringToIndex:160];
[[DatabaseManager getDatabaseManager] addMessageInDatabase:messageField.text];
[messageField setText:@""];
[self updateDetailView];
[messageList reloadData];
}
-(void)handleLongPress : (UILongPressGestureRecognizer *)gesture
{
TableViewCell *cell = nil;
UIMenuController *menu = [UIMenuController sharedMenuController];
if(gesture.state == UIGestureRecognizerStateBegan)
{
CGPoint p = [gesture locationInView:self.messageList];
NSIndexPath *ip = [self.messageList indexPathForRowAtPoint:p];
rowPosition = ip.row;
NSLog(@"row = %d", ip.row);
if(ip)
{
cell = (TableViewCell *)[messageList cellForRowAtIndexPath:ip];
[self becomeFirstResponder];
[menu setMenuItems:nil];
UIMenuItem *copyMenuItem = [[[UIMenuItem alloc] initWithTitle:NSLocalizedString(@"COPY_MESSAGE", @"") action:@selector(copyMessage:)] autorelease];
UIMenuItem *deleteMenuItem = [[[UIMenuItem alloc] initWithTitle:NSLocalizedString(@"DELETE_MESSAGE", @"") action:@selector(deleteMessage:)] autorelease];
if(cell.imFailIndication.image != nil)
{
UIMenuItem *resendMenuItem = [[[UIMenuItem alloc] initWithTitle:NSLocalizedString(@"RESEND_MESSAGE", @"") action:@selector(resendMessage:)] autorelease];
[menu setMenuItems:[NSArray arrayWithObjects:copyMenuItem, deleteMenuItem, resendMenuItem, nil]];
}
else
{
[menu setMenuItems:[NSArray arrayWithObjects:copyMenuItem, deleteMenuItem, nil]];
}
[menu setTargetRect:cell.frame inView:cell.superview];
[menu setMenuVisible:YES animated:YES];
return;
}
}
}
- (void)copyMessage:(id)sender
{
MessageDetailInfo *detailMessageInfo = [messageArray objectAtIndex:rowPosition];
[UIPasteboard generalPasteboard].string = detailMessageInfo.message;
}
- (void)deleteMessage:(id)sender
{
messageDeleteActionSheet = [[UIActionSheet alloc] initWithTitle:NSLocalizedString(@"PROMPT_MESSAGE_DELETE_CONFIRMATION", @"") delegate:self cancelButtonTitle:NSLocalizedString(@"CANCEL_BTN_TITLE", @"") destructiveButtonTitle:NSLocalizedString(@"DELETE_BTN_TITLE", @"") otherButtonTitles:nil, nil];
[messageDeleteActionSheet showFromTabBar:self.tabBarController.tabBar];
}
/*
The view implements this method to conditionally enable or disable commands of the editing menu.
The canPerformAction:withSender method is declared by UIResponder.
*/
- (BOOL)canPerformAction:(SEL)action withSender:(id)sender
{
UIMenuController *menu = (UIMenuController *)sender;
switch ([[menu menuItems] count])
{
case 0:
//This case is to display paste option for Message text field.
if(action == @selector(paste:))
{
return YES;
}
break;
case 2:
if(action == @selector(copyMessage:) || action == @selector(deleteMessage:))
{
return YES;
}
break;
case 3:
if(action == @selector(copyMessage:) || action == @selector(deleteMessage:) || action == @selector(resendMessage:))
{
return YES;
}
break;
default:
break;
}
return NO;
}
- (void)keyboardWillShow:(NSNotification *)notification
{
/*
Reduce the size of the text view so that it's not obscured by the keyboard.
Animate the resize so that it's in sync with the appearance of the keyboard.
*/
NSDictionary *userInfo = [notification userInfo];
// Get the origin of the keyboard when it's displayed.
NSValue* aValue = [userInfo objectForKey:UIKeyboardFrameEndUserInfoKey];
// Get the top of the keyboard as the y coordinate of its origin in self's view's coordinate system. The bottom of the text view's frame should align with the top of the keyboard's final position.
CGRect keyboardRect = [aValue CGRectValue];
// Get the duration of the animation.
NSValue *animationDurationValue = [userInfo objectForKey:UIKeyboardAnimationDurationUserInfoKey];
NSTimeInterval animationDuration;
[animationDurationValue getValue:&animationDuration];
// Animate the resize of the text view's frame in sync with the keyboard's appearance.
[UIView beginAnimations:nil context:NULL];
[UIView setAnimationDuration:animationDuration];
/* change position of messageBarView based on visibility of keypadview. */
CGRect messageBarFrame = messageBarView.frame;
messageBarFrame.origin.y = viewHeight - keyboardRect.size.height - messageBarView.frame.size.height;
messageBarView.frame = messageBarFrame;
if(messageBarFrame.origin.y == (viewHeight - keyboardRect.size.height - messageBarView.frame.size.height))
{
[messageField becomeFirstResponder];
}
/* change height of messageList based on visibility of keypadView. */
CGRect messageListFrame = messageList.frame;
messageListFrame.size.height = messageBarView.frame.origin.y;
messageList.frame = messageListFrame;
[UIView commitAnimations];
/* scroll to table view at last message if messages are available. */
if ([messageList numberOfRowsInSection:0])
{
[messageList scrollToRowAtIndexPath:[NSIndexPath indexPathForRow ([messageList numberOfRowsInSection:0] - 1) inSection:0] atScrollPosition:UITableViewScrollPositionBottom animated:YES];
}
}
- (void)keyboardWillHide:(NSNotification *)notification
{
NSDictionary* userInfo = [notification userInfo];
/*
Restore the size of the text view (fill self's view).
Animate the resize so that it's in sync with the disappearance of the keyboard.
*/
NSValue *animationDurationValue = [userInfo objectForKey:UIKeyboardAnimationDurationUserInfoKey];
NSTimeInterval animationDuration;
[animationDurationValue getValue:&animationDuration];
[UIView beginAnimations:nil context:NULL];
[UIView setAnimationDuration:animationDuration];
/* change position of messageBarView based on visibility of keypadview. */
CGRect newFrame = messageBarView.frame;
newFrame.origin.y = self.view.frame.size.height - messageBarView.frame.size.height;
messageBarView.frame = newFrame;
/* Don't update tableview if datasource has been set nil. */
if(messageList.dataSource != nil)
{
/* change height of messageList based on visibility of keypadView. */
CGRect messageListFrame = messageList.frame;
messageListFrame.size.height = messageBarView.frame.origin.y;
messageList.frame = messageListFrame;
}
[UIView commitAnimations];
}
- (void)didHideEditMenu:(NSNotification *)notification
{
[[UIMenuController sharedMenuController] setMenuItems:nil];
}
- (void)didReceiveMemoryWarning
{
/* Releases the view if it doesn't have a superview. */
[super didReceiveMemoryWarning];
/* Release any cached data, images, etc that aren't in use. */
}
- (void)viewDidUnload
{
[super viewDidUnload];
/* Release any retained subviews of the main view.
e.g. self.myOutlet = nil; */
[[NSNotificationCenter defaultCenter] removeObserver:self name:UIKeyboardWillShowNotification object:nil];
[[NSNotificationCenter defaultCenter] removeObserver:self name:UIKeyboardWillHideNotification object:nil];
[[NSNotificationCenter defaultCenter] removeObserver:self name:UIMenuControllerDidHideMenuNotification object:nil];
}
- (void)viewWillDisappear:(BOOL)animated
{
[super viewWillDisappear:animated];
messageList.delegate = nil;
messageList.dataSource = nil;
}
-(BOOL)navigationShouldPopOnBackButton
{
NSLog(@"navigationShouldPopOnBackButton appearedFromComposeView = %d", [[NSNumber numberWithBool:appearedFromComposeView] intValue]);
if(appearedFromComposeView)
{
[self.navigationController popToRootViewControllerAnimated:YES];
}
return YES; // Process 'Back' button click and Pop view controler
}
- (void)dealloc
{
[messageField release];
[messageList release];
[messageBarView release]
[messageArray release];
[super dealloc];
}
@end