简单的渐隐渐现动画效果

随意写的小Demo,适合慢慢显示弹出框的效果以及切换两个界面，代码很简单，可是项目中很实用，至少对我帮助很大，特此记录，效果如下：

demo.gif

代码如下：

#import "AnimationViewController.h"

@interface AnimationViewController ()
{
    UIView *view1;
    UIButton *btn;
    
    UIView *view2;
    UIButton *btn2;
}

@end

@implementation AnimationViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view.
    self.view.backgroundColor = [UIColor whiteColor];
    self.title = @"动画效果";
    
    //1.动画渐隐渐现效果
    
    view1 = [[UIView alloc] initWithFrame:CGRectMake(30,74 , self.view.frame.size.width-60, 80)];
    view1.backgroundColor = [UIColor infoBlueColor];
    view1.alpha = 1;
    [self.view addSubview:view1];
    
    btn = [UIButton buttonWithType:UIButtonTypeCustom];
    btn.tag = 1;
    [btn setTitle:@"渐隐/渐现" forState:UIControlStateNormal];
    [btn setTitle:@"渐隐/渐现" forState:UIControlStateSelected];
    [btn setTitleColor:[UIColor blueColor] forState:UIControlStateNormal];
    [btn setTitleColor:[UIColor blueColor] forState:UIControlStateSelected];
    [btn addTarget:self action:@selector(btnAction:) forControlEvents:UIControlEventTouchUpInside];
    btn.frame = CGRectMake(70, CGRectGetMaxY(view1.frame)+20, self.view.frame.size.width-140, 30);
    [self.view addSubview:btn];
    
    
    //2.两个view切换
    view2 = [[UIView alloc] initWithFrame:CGRectMake(30,74 , self.view.frame.size.width-60, 80)];
    view2.backgroundColor = [UIColor redColor];
    view2.alpha = 0;
    [self.view addSubview:view2];
    
    btn2 = [UIButton buttonWithType:UIButtonTypeCustom];
    btn2.tag = 2;
    [btn2 setTitle:@"切换" forState:UIControlStateNormal];
    [btn2 setTitle:@"切换" forState:UIControlStateSelected];
    [btn2 setTitleColor:[UIColor blueColor] forState:UIControlStateNormal];
    [btn2 setTitleColor:[UIColor blueColor] forState:UIControlStateSelected];
    [btn2 addTarget:self action:@selector(btnAction:) forControlEvents:UIControlEventTouchUpInside];
    btn2.frame = CGRectMake(70, CGRectGetMaxY(btn.frame)+20, self.view.frame.size.width-140, 30);
    [self.view addSubview:btn2];
}


- (void)btnAction:(UIButton *)sender
{
    if (sender.tag == 1)
    {
        if (!btn.selected)
        {
            [UIView animateWithDuration:1 animations:^{
                view1.alpha = 0;
            } completion:^(BOOL finished) {
                [sender setSelected:YES];
            }];
        }
        else
        {
            [UIView animateWithDuration:1 animations:^{
                view1.alpha = 1;
            } completion:^(BOOL finished) {
                [sender setSelected:NO];
            }];
        }
    }
    else
    {
        if (!btn2.selected)
        {
            [UIView animateWithDuration:0.5 animations:^{
                view2.alpha = 1;
            } completion:^(BOOL finished) {
                [UIView transitionFromView:view1 toView:view2 duration:1 options:UIViewAnimationOptionTransitionCurlUp completion:^(BOOL finished) {
                    [sender setSelected:YES];
                }];
            }];
            
        }
        else
        {
            [UIView transitionFromView:view2 toView:view1 duration:1 options:UIViewAnimationOptionTransitionCrossDissolve completion:^(BOOL finished) {
                [sender setSelected:NO];
            }];
        }
    }
    
}

Tip

view的渐隐渐现就是设置view的alpha，设置动画时长即可。