我试图实现的方法是将按钮设置为0.5 alpha，然后在3秒的时间内将其设置为1。在四个按钮上执行5次后，代码块就完成了。我正在努力找到一种可以实现这一目标的方法，因为现在下面的块将是一个无限循环，当我希望它只能执行一次。
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;
}
答案 0 :(得分：1)
当您将按钮的alpha设置为0.5然后立即设置为1时，按钮的alpha将不会设置动画。你可以了解这个片段
[UIView animateWithDuration:0.3 animations:^{
[your_btn setAlpha:0.5];
} completion:^(BOOL finished) {
if(finished)
[self performSelector:@selector(revertAlphaToOne) withObject:nil afterDelay:0.5];
}];
在revertAlphaToOne方法中，您可以将按钮的alpha恢复为1
[UIView animateWithDuration:0.3 animations:^{
[your_btn setAlpha:1.0];
} completion:nil
}];
根据您的喜好调整时间变量和/或在第一个块的完成块中调用第二个片段。
答案 1 :(得分：0)
问题在于，在案例1和案例2中，您将alpha值设置为0.5，然后立即返回1。因此，当动画开始时，它只是1并将保持不变。只需删除第二个分配，动画就会将alpha更改为0.5。 PS：如前所述，生成的随机数是0到4，而不是1到5。
答案 2 :(得分：0)
好吧，我已经使用这个网站好几年了，我应该回复一个很好的答案。
我构建了a project并完成了您想要的功能。一些说明：
- 关键是递归！您需要为淡出设置设置动画（使用我提供的功能），并在完成后使用相同的功能设置淡入淡出动画。完成后，运动递归并准备调用自己（beginAnimations），直到所有的整数= 5。
- 我决定从1-> .5-> 1淡出，因为.5 alpha让我讨厌。如果你想让它逆转，不应该很难切换它。
- 要确保没有按钮消失超过五次，您需要声明并增加与每个按钮对应的int。
- 使用arc4random（），而不是随机（）。随机用于调试，因为每次都会得到相同的结果。
- 保持你的开关盒直;很难理解你想要在他们之间做些什么。在此注释中，使用break和默认语句！祝你在应用程序中使用所有这些好运。
的.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