嵌套动画块导致“分段错误”

Question

我尝试使用以下代码一个接一个地显示三个图像：

image_1.alpha = 0.0;
image_2.alpha = 0.0;
image_3.alpha = 0.0;

[UIView animateWithDuration:0.25
                 animations:^{
                     image_1.alpha = 1.0;
                 } completion:^(BOOL finished) {
                     [UIView animateWithDuration:0.25
                                      animations:^{
                                          image_2.alpha = 1.0;
                                      } completion:^(BOOL finished) {
                                          [UIView animateWithDuration:0.25
                                                           animations:^{
                                                               image_3.alpha = 1.0;
                                                           } completion:^(BOOL finished) {
                                                               ;
                                                           }];
                                      }];
                 }];

给出：internal compiler error: Segmentation fault

如果嵌套包含两个动画块，则没有错误。嵌套动画块是不允许的还是有一些限制？