Words falling from the top of screen in iphone - iphone

Question

Im developing a word finding app.Here i want some words to fall from the top of screen of iphone.
There will be a red line at the bottom of screen.
User have to select the correct word before reaching a red line.
So how can i implement the falling effect in iphone.(i.e words falling effect).
Can anyone please help me with this.
Thanks in advance.

Answer 1

You can implement this using UIView animations. This sample code is all within a view controller, with a single label, fallingLabel added to the view. You can expand it to include multiple labels.
The key point is to import the QuartzCore framework. This gives you access to the presentationLayer of a view, which holds the current state of an animating view. You add the framework to your project in the project summary part of Xcode, then put the following in the top of your view controller's implementation file:
#import <QuartzCore/QuartzCore.h>
The following code animates the dropping of the label. It will increase in speed as it falls due to the UIViewAnimationOptionCurveEaseIn setting, giving you a convincing gravity effect.
self.fallingLabel.center = CGPointMake(160,50);
[UIView animateWithDuration:3
delay:0
options:UIViewAnimationOptionCurveEaseIn
animations:^{self.fallingLabel.center = CGPointMake(160,400);}
completion:nil];
Now, you need to implement touch handling. This is not done on the label, as internally it will think it is already at the bottom of the screen. You handle the touches in your view controller:
-(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
UITouch *touch = [touches anyObject];
CGPoint touchLocation = [touch locationInView:self.view];
if ([self.fallingLabel.layer.presentationLayer hitTest:touchLocation])
{
NSLog(#"Label was touched");
CALayer *presLayer = self.fallingLabel.layer.presentationLayer;
[UIView animateWithDuration:0
delay:0
options:UIViewAnimationOptionBeginFromCurrentState
animations:^{self.fallingLabel.frame = presLayer.frame;}
completion:nil];
}
}
Here, what is happening is that the presentation layer is being queried to see if the touch falls within it's current bounds. If so, we then start a new animation, which starts from the current state - in this case all I have done is stop the falling of the label, but you could implement anything you like here.
If you have multiple falling labels you can try the hitTest on the presentation layer of each one until you find the one that has been touched.

Answer 2

try to use usual animations blocks, but run than in separate theard:
NSOperationQueue *_queue;
_queue = [[NSOperationQueue alloc] init];
SEL selector = #selector(fallWord);
NSMethodSignature *signature = [self methodSignatureForSelector:selector];
NSInvocation *inv = [NSInvocation invocationWithMethodSignature:signature];
[inv setTarget:self];
[inv setSelector:selector];
NSInvocationOperation *fall= [[[NSInvocationOperation alloc] initWithInvocation:inv] autorelease];
[_queue addOperation:fall];
then, implement fallWord method, where you will set an animatin of falling:
UILabel *lb = [[UILabel alloc] initWithFrame:CGRectMake(<#CGFloat x#>, <#CGFloat y#>, <#CGFloat width#>, <#CGFloat height#>)];
[UIView animateWithDuration:1
delay:0
options:UIViewAnimationOptionCurveLinear
animations:^{
[lb setCenter:CGPointMake(<#CGFloat x#>, <#CGFloat y#>)];
} completion:nil];
then, you will need to implement touches and in method
-(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
NSUInteger touchCount = 0;
for (UITouch *touch in touches) {
[self dispatchFirstTouchAtPoint:[touch locationInView:self] forEvent:nil];
touchCount++;
}
}
check if touch coodinates inside your UILabel's frame

Answer 3

Cocos2d combined with box2d or chipmunk will help you achieve a falling affect (simulating gravity towards the bottom of the screen).
I will give a general plan with Cocos2d / chipmunk
Learn both.
Cocos2d - CCLabelTTF, CCLayer, CCSprite, CCTouch recognition, how to schedule a timer with cocos2d
Chipmunk - bodies, gravity, using the timer set up with cocos2d to step through the physics, calling a C static void function to update the CCLabelTTF's that are still on screen, removing those objects that aren't on screen (past the red line), and how to use the Cocos2d touch methods to verify if you hit a word or not.
ie method
-(void)ccTouchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
There are great starter documents on Cocos2d's site and not so great documentation for chipmunk, but you can find tutorials on hooking that in.
I am not sure if UIKit animations can be interrupted how they will need to be in your app.
In any implementation, you will also need to ensure your view displaying the text isn't bigger than the text.
If you take the cocos2d + physics engine route to achieve your goal, you will be in good shape to learn how to make an even more complex game.

Answer 4

You are actually looking for AutoComplete textbox. Basically there is no such thing exist in iPhone. but with the help of UIPicker view you can provide such effect