List of Buttons lighting up at random - objective-c

Question

The method im trying to achieve is set a button to 0.5 alpha then back to 1 in the space of three seconds. After its executed 5 time on the four buttons the block of code is finished. Im struggling to find a way in which this can be achieved becasue right now the block below will be an infinite loop when i want it to be only executed through once.
int rand=random()%5;
switch (rand) {
case 1:{
[UIView beginAnimations:NULL context:NULL];
[UIView setAnimationDuration:5.0];
[btnYellow setAlpha:0.5];
[btnYellow setAlpha:1];
[UIView commitAnimations];
}
break;
case 2:
[UIView beginAnimations:NULL context:NULL];
[UIView setAnimationDuration:5.0];
[btnRed setAlpha:0.5];
[btnRed setAlpha:1];
[UIView commitAnimations];
break;
case 3:
[UIView beginAnimations:NULL context:NULL];
[UIView setAnimationDuration:5.0];
[btnBlue setAlpha:1];
[UIView commitAnimations];
case 4:
[UIView beginAnimations:NULL context:NULL];
[UIView setAnimationDuration:5.0];
[btnGreen setAlpha:1];
[UIView commitAnimations];
break;
case 5:
[UIView beginAnimations:NULL context:NULL];
[UIView setAnimationDuration:5.0];
[btnYellow setAlpha:1];
[UIView commitAnimations];
break;
}

Answer 1

As you are setting up the button's alpha to 0.5 and then to 1 immediately, the button's alpha won't animate. You can get an idea this snippet
[UIView animateWithDuration:0.3 animations:^{
[your_btn setAlpha:0.5];
} completion:^(BOOL finished) {
if(finished)
[self performSelector:#selector(revertAlphaToOne) withObject:nil afterDelay:0.5];
}];
And in that revertAlphaToOne Method, you can revert the button's alpha to 1 as
[UIView animateWithDuration:0.3 animations:^{
[your_btn setAlpha:1.0];
} completion:nil
}];
Adjust the time variables according to your likings And/Or call the second snippet in the first block's completion block itself.

Answer 2

Well, I've been using this site for several years, and I was due for a nice thorough answer to give back.
I built a project and accomplished the functionality you desired. Some notes:
-The key is recursion! You need to animate the fade out (using the function I provided) and, upon completion, animating the fade back in using the same function. Once completed, exercise recursion and prepare to call itself (beginAnimations) until all ints=5.
-I decided to fade from 1->.5->1 because the .5 alpha was annoying me. Shouldn't be hard to switch that around if you want it reversed.
-To make sure no button fades more than fives times, you need to declare and increment an int corresponding to each button.
-Use arc4random(), not random(). Random is for debugging as you will have the same result every time.
-Keep your switch case's straight; was hard to understand what you wanted to be different between them. On this note, use breaks and a default statement! Good luck employing all this into your app.
.m
#import "ViewController.h"
#interface ViewController ()
#end
#implementation ViewController
- (void)viewDidLoad
{
[super viewDidLoad];
[self.view setBackgroundColor:[UIColor blackColor]];
//declare and define button specifics
btnYellow = [UIButton buttonWithType: UIButtonTypeCustom];
[btnYellow setBackgroundColor: [UIColor yellowColor]];
btnYellow = [self buttonTraits:btnYellow];
[btnYellow setFrame: CGRectMake(20, 20, 280, 30)];
[btnYellow setTitleColor:[UIColor blackColor] forState:UIControlStateNormal];
[btnYellow.titleLabel setFont:[UIFont boldSystemFontOfSize:14]];
btnRed = [UIButton buttonWithType: UIButtonTypeCustom];
[btnRed setBackgroundColor: [UIColor redColor]];
[btnRed setFrame: CGRectMake(20, 60, 280, 30)];
[btnRed setTitleColor:[UIColor blackColor] forState:UIControlStateNormal];
[btnRed.titleLabel setFont:[UIFont boldSystemFontOfSize:14]];
btnBlue = [UIButton buttonWithType: UIButtonTypeCustom];
[btnBlue setFrame: CGRectMake(20, 100, 280, 30)];
[btnBlue setTitleColor:[UIColor blackColor] forState:UIControlStateNormal];
[btnBlue.titleLabel setFont:[UIFont boldSystemFontOfSize:14]];
[btnBlue setBackgroundColor: [UIColor blueColor]];
btnGreen = [UIButton buttonWithType: UIButtonTypeCustom];
[btnGreen setFrame: CGRectMake(20, 140, 280, 30)];
[btnGreen setTitleColor:[UIColor blackColor] forState:UIControlStateNormal];
[btnGreen.titleLabel setFont:[UIFont boldSystemFontOfSize:14]];
[btnGreen setBackgroundColor: [UIColor greenColor]];
//add buttons to the view
[self.view addSubview:btnYellow];
[self.view addSubview:btnRed];
[self.view addSubview:btnBlue];
[self.view addSubview:btnGreen];
//set the counting ints to 0
yellowCount = 0, redCount = 0, blueCount = 0, greenCount = 0;
//run through the animations the first time
[self beginAnimations];
}
-(void)beginAnimations
{
if (!(yellowCount==5 && redCount==5 && blueCount == 5 && greenCount == 5))
{
//if you want 5 buttons, define another one, then the next line would be int rand=random()%6;
int rand=((arc4random()%5)+1); //arc4random gives 0-3; add 1 for 1-4
switch (rand) {
case 1:
{
//make sure this button hasn't gone through the process 5 times already
if (yellowCount<5)
{
//increment the button's count
yellowCount++;
//set up animation with 1.5 second duration (alpha decline from 1->.5)
[UIView animateWithDuration:1.5 delay:0 options: UIViewAnimationOptionCurveEaseOut animations:^{
[btnYellow setAlpha:.5];
} completion:^(BOOL finished)
{
if(finished==TRUE)
{
[UIView animateWithDuration:1.5 delay:0 options: UIViewAnimationOptionCurveEaseOut animations:^{
[btnYellow setAlpha:1];
} completion:^(BOOL finished) {
if(finished==TRUE)
{
[self beginAnimations];
}
}];
}
}];
}
else
{
//restart the animation hoping to get another button that hasn't gone 5 times yet
[self beginAnimations];
}
}
break; //you forgot a break here. can cause troubles
case 2:
{
if (redCount<5)
{
redCount++;
[UIView animateWithDuration:1.5 delay:0 options: UIViewAnimationOptionCurveEaseOut animations:^
{
[btnRed setAlpha:.5];
} completion:^(BOOL finished)
{
if(finished==TRUE)
{
[UIView animateWithDuration:1.5 delay:0 options: UIViewAnimationOptionCurveEaseOut animations:^{
[btnRed setAlpha:1];
} completion:^(BOOL finished) {
if(finished==TRUE)
{
[self beginAnimations];
}
}];
}
}];
}
else
{
[self beginAnimations];
}
}
break;
case 3:
{
if (blueCount<5)
{
blueCount++;
[UIView animateWithDuration:1.5 delay:0 options: UIViewAnimationOptionCurveEaseOut animations:^
{
[btnBlue setAlpha:.5];
} completion:^(BOOL finished)
{
if(finished==TRUE)
{
[UIView animateWithDuration:1.5 delay:0 options: UIViewAnimationOptionCurveEaseOut animations:^{
[btnBlue setAlpha:1];
} completion:^(BOOL finished) {
if(finished==TRUE)
{
[self beginAnimations];
}
}];
}
}];
}
else
{
[self beginAnimations];
}
}
break; //you forgot another break here. can cause troubles
case 4:
{
if (greenCount<5)
{
greenCount++;
[UIView animateWithDuration:1.5 delay:0 options: UIViewAnimationOptionCurveEaseOut animations:^
{
[btnGreen setAlpha:.5];
} completion:^(BOOL finished)
{
if(finished==TRUE)
{
[UIView animateWithDuration:1.5 delay:0 options: UIViewAnimationOptionCurveEaseOut animations:^{
[btnGreen setAlpha:1];
} completion:^(BOOL finished) {
if(finished==TRUE)
{
[self beginAnimations];
}
}];
}
}];
}
else
{
[self beginAnimations];
}
}
break;
default:
{
//in case of an awry number, restart the process (be wary; infinite loop potential)
[self beginAnimations];
}
break; //it is of good practice to always have a default method in switch statements
}
}
else
{
//the process is complete
}
}
- (void)didReceiveMemoryWarning
{
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
.h
#import <UIKit/UIKit.h>
#interface ViewController : UIViewController
{
UIButton *btnYellow;
UIButton *btnRed;
UIButton *btnBlue;
UIButton *btnGreen;
int yellowCount;
int redCount;
int blueCount;
int greenCount;
}
#end

Answer 3

The problem is that in cases 1 and 2, you set the alpha value to 0.5 and then IMMEDIATELY back to 1. So when the animation starts, it is simply 1 and will remain so. Just delete the 2nd assignment, and the animation will change alpha to 0.5. PS: As already mentioned, the random number generated is from 0 to 4, and not from 1 to 5.