Question

我编写了下面的代码，使用NSTimer将图像从顶部移动到按钮。但是，当我运行它时，我不能单独分配图像。基本上，图像留下痕迹。我想要的是逐帧移动图像。我错过了什么？

-(void)printOut:(NSTimer*)timer1;
{

    image = [[UIImageView alloc] initWithFrame:CGRectMake(50, -50+m, 50, 50)];
    [image setImage:[UIImage imageNamed:[NSString stringWithFormat:@"image.png"]]];

    CGRect oldFrame = image.frame;
    image.frame = CGRectMake(oldFrame.origin.x+5, oldFrame.origin.y, oldFrame.size.width, oldFrame.size.height);

    [self.view addSubview:image];

    m++;
    if (m == 1000) {
        [timer1 invalidate];
    }

}

编辑：我不想使用动画。因为稍后我需要使用碰撞检测，因此无法控制动画的坐标。

Answer 1

每次为自己分配和添加子视图。您何时删除ImageView以消除上一个ImageView。因此，请在分配之前尝试删除图像。试试这个

-(void)printOut:(NSTimer*)timer1;
{
[image removeFromSuperview];
image = nil;
image = [[UIImageView alloc] initWithFrame:CGRectMake(50, -50+m, 50, 50)];
[image setImage:[UIImage imageNamed:[NSString stringWithFormat:@"image.png"]]];

CGRect oldFrame = image.frame;
image.frame = CGRectMake(oldFrame.origin.x+5, oldFrame.origin.y, oldFrame.size.width, oldFrame.size.height);

[self.view addSubview:image];

m++;
if (m == 1000) {
    [timer1 invalidate];
}
}

Answer 2

这样做：

image.frame = (top frame here)

[UIView animateWithDuration:0.4 delay:0 options:UIViewAnimationOptionCurveEaseOut animations:^{ 
//change time duration according to requirement
// animate it to the bottom of view
image.frame = (bottom frame here)
} completion:^(BOOL finished){
// if you want to do something once the animation finishes, put it here
}];

iphone开发：使用NSTimer进行动画制作

2 个答案: