ios – animationControllerForPresentedController未调用

我有一个像这样的ViewController：

@interface ViewController () <UIViewControllerTransitioningDelegate>
@property (nonatomic,strong) UILabel *testLabel;
@property (nonatomic,strong) UIButton *button;
@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];

    self.view.BACkgroundColor = [UIColor whiteColor];
    self.transitioningDelegate = self;

    _testLabel = [[UILabel alloc] init];
    _testLabel.text = @"View 1";

    [self.view addSubview:_testLabel];



    [_testLabel mas_makeConsTraints:^(MASConsTraintMaker *makE) {
        make.width.equalTo(self.view);
        make.height.equalTo(@50);
        make.centerX.equalTo(self.view);
        make.top.equalTo(self.mas_topLayoutGuidE);
    }];

    _button = [[UIButton alloc] init];
    [_button addTarget:self action:@SELEctor(push)forControlEvents:UIControlEventTouchUpInside];
    [_button settitleColor:[UIColor redColor] forState:UIControlStateNormal];
    [_button settitle:@"Show View" forState:UIControlStateNormal];
    [self.view addSubview:_button];

    [_button mas_makeConsTraints:^(MASConsTraintMaker *makE) {
        make.center.equalTo(self.view);
        make.width.and.height.equalTo(@50);
    }];
}

- (void)push {
    NSLog(@"Push controller");
    BACkViewController *vc = [[BACkViewController alloc] init];
    [self.navigationController presentViewController:vc animated:YES completion:nil];
}

-(id<UIViewControllerAnimatedTransitioning>)animationControllerForPresentedController:(UIViewController *)presented presenTingController:(UIViewController *)presenTing sourceController:(UIViewController *)source {
    TurnAnimationController *an = [[TurnAnimationController alloc] init];
    an.flipDirection = CEDirectionHorizontal;
    return an;
}

永远不会调用animationControllerForPresentedController方法,因此我的动画永远不会被执行.我没有看到问题？我正在将transitioningDelegate设置为自我？

有人有想法吗？