淡出淡入

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.
    
    //UIView
    UIView *view=[[UIView alloc]initWithFrame:CGRectMake(10, 100, 100, 200)];
    view.backgroundColor=[UIColor redColor];
    [self.view addSubview:view];
    
    //淡出
    //[self fadeOut:view];
    
    //淡入
    //[self fadeIn:view];
    
}

//淡出
-(void) fadeOut:(UIView *)view
{
    CGContextRef context = UIGraphicsGetCurrentContext();
    [UIView beginAnimations:nil context:context];
    [UIView setAnimationCurve:UIViewAnimationCurveEaseInOut];
    [UIView setAnimationDuration:0.3];
    [view setAlpha:0.0f];
    [UIView commitAnimations];
}

//淡入
-(void) fadeIn:(UIView *)view
{
    CGContextRef context = UIGraphicsGetCurrentContext();
    [UIView beginAnimations:nil context:context];
    [UIView setAnimationCurve:UIViewAnimationCurveEaseInOut];
    [UIView setAnimationDuration:0.3];
    [view setAlpha:1.0f];
    [UIView commitAnimations];
}