我试图在用户定义它时沿着路径移动飞机,类似于飞行控制中的控件。我能够绘制路径,尽管效率低下,但我无法让飞机顺利地沿着路径设置动画。
我最初尝试使用通过更改位置提供的隐式动画来沿路径移动飞机,但因为它不允许我改变动画的速度,所以飞机的行为很糟糕。
我现在正在尝试递归地使用动画块,但是完成块被调用得太快了,导致飞机只跟随绘制的路径。
这是设置代码:
- (CALayer *)plane{
if(!_plane){
_plane = [CALayer layer];
UIImage *planeImage = [UIImage imageNamed:@"airplane.png"];
_plane.bounds = CGRectMake(20.0, 20.0, planeImage.size.width, planeImage.size.height);
_plane.contents = (id)(planeImage.CGImage);
[self.layer addSublayer:_plane];
}
return _plane;
}
- (void)touchesEnded:(NSSet *)touches
withEvent:(UIEvent *)event{
if(isDrawingPath){
[self.trackPath addLineToPoint:[[touches anyObject] locationInView:self]];
NSLog(@"%@", self.trackPath);
UITouch *touch = [touches anyObject];
CGPoint toPoint = [touch locationInView:self];
//now, save each point in order to make the path
[self.points addObject:[NSValue valueWithCGPoint:toPoint]];
[self setNeedsDisplay];
[self goToPointWithIndex:0];
}
isDrawingPath = NO;
}
此实现有效,但效果不佳。飞机跟随路径,但它是波涛汹涌的:
- (void)goToPointWithIndex:(NSNumber *)indexer{
int toIndex = [indexer intValue];
if(toIndex < self.points.count){
//extract the value from array
CGPoint toPoint = [(NSValue *)[self.points objectAtIndex:toIndex] CGPointValue];
CGPoint pos = self.plane.position;
float delay = PLANE_SPEED * (sqrt( pow(toPoint.x - pos.x, 2) + pow(toPoint.y - pos.y, 2)));
self.plane.position = toPoint;
// Allows animation to continue running
if(toIndex < self.points.count - 1){
toIndex++;
}
//float delay = 0.2;
NSLog(@"%f", delay);
//repeat the method with a new index
//this method will stop repeating as soon as this "if" gets FALSE
NSLog(@"index: %d, x: %f, y: %f", toIndex, toPoint.x, toPoint.y);
[self performSelector:@selector(goToPointWithIndex:) withObject:[NSNumber numberWithInt:toIndex] afterDelay:delay];
}
}
这就是我试图用块做的事情。它只是跳到绘制路径的末尾,而不是跟随整个事物。
- (void)goToPointWithIndex:(int)toIndex{
if(self.resetPath) return;
//extract the value from array
if(toIndex < self.points.count) {
CGPoint toPoint = [(NSValue *)[self.points objectAtIndex:toIndex] CGPointValue];
NSLog(@"index: %d, x: %f, y: %f", toIndex, toPoint.x, toPoint.y);
CGPoint pos = self.plane.position;
//float delay = PLANE_SPEED * (sqrt( pow(toPoint.x - pos.x, 2) + pow(toPoint.y - pos.y, 2)));
// Allows animation to continue running
if(toIndex < self.points.count - 1){
toIndex++;
}
[UIView animateWithDuration:0.2
animations:^{
self.plane.position = toPoint;
}
completion:^(BOOL finished) {
if(finished == YES) {NSLog(@"Complete");[self goToPointWithIndex:toIndex];}
}];
}
}
我不知道我哪里出错了。我是objective-c和blocks的新手。完成块是否应该在动画开始后立即运行?这对我来说没有意义,但这是我能找到的唯一解释。
编辑:我最终使飞机成为 UIView,所以我仍然可以使用块动画。CALayer 事务根本不喜欢我的递归。