Send a Delegate message from UIPopover to Main UIViewController

问题

I'm trying to use a Button in my UIPopover to create a UITextView in my Main UIViewController the code I have looks something like this (PopoverView.h file):

@protocol PopoverDelegate <NSObject> 

- (void)buttonAPressed;

@end

@interface PopoverView : UIViewController <UITextViewDelegate> {  //<UITextViewDelegate>

    id <PopoverDelegate> delegate;
    BOOL sendDelegateMessages;
}
@property (nonatomic, retain) id delegate;
@property (nonatomic) BOOL sendDelegateMessages;
@end

Then in my PopoverView.m file:

- (void)viewDidLoad
{
    [super viewDidLoad];

UIButton * addTB1 = [UIButton buttonWithType:UIButtonTypeRoundedRect];
addTB1.frame = CGRectMake(0, 0, 100, 50);
[addTB1 setTitle:@"Textbox One" forState:UIControlStateNormal];
[self.view addSubview:addTB1];    // Do any additional setup after loading the view from its nib.
[addTB1 addTarget:self action:@selector(buttonAPressed) 
forControlEvents:UIControlEventTouchUpInside];
}

- (void)buttonAPressed
{
    NSLog(@"tapped button one");

    if (sendDelegateMessages)
        [delegate buttonAPressed];
}

And also in my MainViewController.m :

- (void)buttonAPressed {

    NSLog(@"Button Pressed");
    UITextView *textfield = [[UITextView alloc] init];
    textfield.frame = CGRectMake(50, 30, 100, 100);
    textfield.backgroundColor = [UIColor blueColor];
    [self.view addSubview:textfield];
}

I'm using a delegate protocol to link the popover and the ViewController but I'm stuck on how I get my BOOL statement to link the -(void)buttonAPressed in the PopoverView and MainViewController so that when I press the button in the Popover a textview appears in the Main VC. How would I go about doing this?

回答1:

In MainViewController, where you create PopoverView, be sure to set its delegate property otherwise sending messages to delegate in PopoverView will do nothing.

For example, in MainViewController.m:

PopoverView *pov = [[PopoverView alloc] initWithNibName:nil bundle:nil];
pov.delegate = self;  // <-- must set this
thePopoverController = [[UIPopoverController alloc] initWithContent...

I am not sure why you need the sendDelegateMessages variable. Even with that bool, you must set the delegate property so PopoverView has an actual object reference to send the messages to.

If you want to make sure the delegate object has implemented the method you're about to call, you can do this instead:

if ([delegate respondsToSelector:@selector(buttonAPressed)])
    [delegate buttonAPressed];

Also, the delegate property should be declared using assign (or weak if using ARC) instead of retain (see Why use weak pointer for delegation? for an explanation):

@property (nonatomic, assign) id<PopoverDelegate> delegate;

Another thing is if you're not using ARC, you need to add [textfield release]; at the end of the buttonAPressed method in MainViewController to avoid a memory leak.

来源：https://stackoverflow.com/questions/8884522/send-a-delegate-message-from-uipopover-to-main-uiviewcontroller

标签

ios

uiviewcontroller

delegates

uitextview

uipopovercontroller