Question

我想做一个响应设备动作的动画，即使UI线程暂时忙，我也希望它保持平滑。动画包括更改CALayer的贝塞尔曲线路径。我试过从辅助线程做到这一点，但我偶尔会挂起主线程有一个已删除的堆栈。我在做什么完全没有希望？这是我在线程中所做的：

[CATransaction lock];
[CATransaction setValue:(id)kCFBooleanTrue
                 forKey:kCATransactionDisableActions];
[CATransaction begin];
myLayer.path = [UIBezierPath bezierPathWithOvalInRect:theRect].CGPath;
myLayer.bounds = theBounds;
[CATransaction commit];

[CATransaction flush];
[CATransaction setValue:(id)kCFBooleanFalse
                 forKey:kCATransactionDisableActions];
[CATransaction unlock];

Answer 1

这是我的版本。

dispatch_async(dispatch_get_main_queue(), ^{
            myLayer.path = [UIBezierPath bezierPathWithOvalInRect:theRect].CGPath;
            myLayer.bounds = theBounds;
        });

Dispatch队列为您提供了从本地范围提取变量的优势，而无需担心实现中间数据结构。

Answer 2

禁止从除uithread之外的任何线程更新ui 所以你必须做以下事情：

- (void) updateUI
{
[CATransaction lock];
[CATransaction setValue:(id)kCFBooleanTrue
                 forKey:kCATransactionDisableActions];
[CATransaction begin];
myLayer.path = [UIBezierPath bezierPathWithOvalInRect:theRect].CGPath;
myLayer.bounds = theBounds;
[CATransaction commit];

[CATransaction flush];
[CATransaction setValue:(id)kCFBooleanFalse
                 forKey:kCATransactionDisableActions];
[CATransaction unlock];
}

和其他帖子

[self performSelectorOnMainThread:@selector(updateUI) withObject:nil waitUntilDone:YES];

从后台线程更改CALayer的属性是否安全？

2 个答案: