How to display temporary popup message on iPhone/iPad/iOS

Create a class that inherits from UIAlertView. In your constructor just call [super init] and then add any view you want as a subview. You can even design this view in Interface Builder. Something like this:

- (id)initWithMessage:(NSString *)message dismissAfter:(NSTimeInterval)interval
{
  if ((self = [super init]))
  {
     CustomView * customView = [[[CustomView alloc] init] autorelease]; // or load from NIB
     [self addSubview:customView];
     [self performSelector:@selector(dismissAfterDelay) withObject:nil afterDelay:interval];
  }
  return self;
}

- (void)dismissAfterDelay
{
  [self dismissWithClickedButtonIndex:0 animated:YES]; 
}

To display your custom alert view just init it, and call show as with a regular UIAlertView.

CustomAlertView * cav = [[CustomAlertView alloc] initWithMessage:@"Doing Something];
[cav show];
[cav release];

As an nice side-effect, when you present this view the background will darken and you will get the nice wobbly animation for any alert view.

Use UIAlertView. Here's a quick link to a simple example:

UIAlertView

Edited: Sorry, didn't see about disappearing on it's own. I think you need to have some confirmation by users of messages received. UIAlertView pretty much accomplishes that. Not sure if you have it gradually fade away unless you're in an app with a view that has a timer or event based delay that will show a view and then eventually remove it.

Second edit: Found a way to implement it. You can manually call the dismiss function after some set time that you've designated. (Sorry for the messy post) It would look something like this:

//Create UIAlertView alert
alert = [[UIAlertView alloc] initWithTitle:@"Title" message:@"Some message" delegate:self cancelButtonTitle:@"Cancel" otherButtonTitles: nil];

//After some time
[alert dismissWithClickedButtonIndex:0 animated:TRUE];

I ended up creating my own class. Didn't inherit from UIAlertView. General structure is,

-(id)initWithText:(NSString *)msg {
    // Create a view. Put a label, set the msg
    CALayer *layer = self.layer;
    layer.cornerRadius = 8.0f;
    ...
    self.backgroundColor = [UIColor colorWithWhite:0 alpha:0.8];
    [self performSelector:@selector(dismiss:) withObject:nil afterDelay:2.0];
    [self setAutoresizesSubviews:FALSE];
    return self;
}


- (void)dismiss:(id)sender {
    // Fade out the message and destroy self
    [UIView animateWithDuration:0.5 
                 animations:^  { self.alpha = 0; }
                 completion:^ (BOOL finished) { [self removeFromSuperview]; }];
}

I created an Android-Kind toast, pretty simple because I don't need more functionality in it for now.

When it is shown it is added at the bottom of the parent's view, so if that view is the VC's view then it will be at the bottom center of the device.

The frame is autoadjusted to the text length.

You use it doing: [self.view addSubview: [[ToastAlert alloc] initWithText: @"Sent"]];, it will be auto-removed so no reference is needed.

The class:

ToastAlert.h

@interface ToastAlert : UILabel {

}

- (id)initWithText: (NSString*) msg;

@end

ToastAlert.m

#import "ToastAlert.h"
#import <QuartzCore/QuartzCore.h>

@implementation ToastAlert

#define POPUP_DELAY  1.5

- (id)initWithText: (NSString*) msg
{

    self = [super init];
    if (self) {

        self.backgroundColor = [UIColor colorWithWhite:0 alpha:0.7];
        self.textColor = [UIColor colorWithWhite:1 alpha: 0.95];
        self.font = [UIFont fontWithName: @"Helvetica-Bold" size: 13];
        self.text = msg;
        self.numberOfLines = 0;
        self.textAlignment = UITextAlignmentCenter;
        self.autoresizingMask = UIViewAutoresizingFlexibleTopMargin | UIViewAutoresizingFlexibleLeftMargin | UIViewAutoresizingFlexibleRightMargin;


    }
    return self;
}

- (void)didMoveToSuperview {

    UIView* parent = self.superview;

    if(parent) {

        CGSize maximumLabelSize = CGSizeMake(300, 200);
        CGSize expectedLabelSize = [self.text sizeWithFont: self.font  constrainedToSize:maximumLabelSize lineBreakMode: NSLineBreakByTruncatingTail];

        expectedLabelSize = CGSizeMake(expectedLabelSize.width + 20, expectedLabelSize.height + 10);

        self.frame = CGRectMake(parent.center.x - expectedLabelSize.width/2,
                                parent.bounds.size.height-expectedLabelSize.height - 10,
                                expectedLabelSize.width,
                                expectedLabelSize.height);

        CALayer *layer = self.layer;
        layer.cornerRadius = 4.0f;

        [self performSelector:@selector(dismiss:) withObject:nil afterDelay:POPUP_DELAY];
    }
}

- (void)dismiss:(id)sender {
    // Fade out the message and destroy self
    [UIView animateWithDuration:0.6  delay:0 options: UIViewAnimationOptionAllowUserInteraction
                     animations:^  { self.alpha = 0; }
                     completion:^ (BOOL finished) { [self removeFromSuperview]; }];
}

@end