首先，支持並感謝@wazrx 的 http://www.jianshu.com/p/45434f73019e和@onevcat 的https://onevcat.com/2013/10/vc-transition-in-ios7/ 對於轉場動畫的講解和實現，非常詳細，本人也是看過他們的文章後受的啟發，快速實現了基於本項目需求的轉場動畫效果。

效果如下：（gif是我們的美術大師幫忙做的演示動效，實際的效果要比這個好，可通過文章最後鏈接下載我們的app：檸檬跑步，查看效果）

我的需求是兩個頁面push、pop之間的切換，所以自定義了push的轉場動畫，首先需要個遵循協議的管理對象，並實現其兩個方法：
XWCircleSpreadTransition.h

#import typedef NS_ENUM(NSUInteger, XWCircleSpreadTransitionType) {
    XWCircleSpreadTransitionTypePush = 0,
    XWCircleSpreadTransitionTypePop
};

@interface XWCircleSpreadTransition : NSObject@property (nonatomic, assign) XWCircleSpreadTransitionType type;

+ (instancetype)transitionWithTransitionType:(XWCircleSpreadTransitionType)type;
- (instancetype)initWithTransitionType:(XWCircleSpreadTransitionType)type;
@end

XWCircleSpreadTransition.m

#import "XWCircleSpreadTransition.h"

@implementation XWCircleSpreadTransition

+ (instancetype)transitionWithTransitionType:(XWCircleSpreadTransitionType)type{
    return [[self alloc] initWithTransitionType:type];
}

- (instancetype)initWithTransitionType:(XWCircleSpreadTransitionType)type{
    self = [super init];
    if (self) {
        _type = type;
    }
    return self;
}

- (NSTimeInterval)transitionDuration:(id)transitionContext{
    return 0.7;
}

- (void)animateTransition:(id)transitionContext{
    switch (_type) {
        case XWCircleSpreadTransitionTypePush:
            [self presentAnimation:transitionContext];
            break;

        case XWCircleSpreadTransitionTypePop:
            [self dismissAnimation:transitionContext];
            break;
    }
}

- (void)dismissAnimation:(id)transitionContext{
    UIViewController *toVC = [transitionContext viewControllerForKey:UITransitionContextToViewControllerKey];
    UIViewController *fromVC = [transitionContext viewControllerForKey:UITransitionContextFromViewControllerKey];
    UIView *containerView = [transitionContext containerView];
    [containerView insertSubview:toVC.view atIndex:0];
    //畫兩個圓路徑
    CGFloat radius = sqrtf(containerView.frame.size.height * containerView.frame.size.height + containerView.frame.size.width * containerView.frame.size.width) / 2;
    UIBezierPath *startCycle = [UIBezierPath bezierPathWithArcCenter:containerView.center radius:radius startAngle:0 endAngle:M_PI * 2 clockwise:YES];
//    UIBezierPath *endCycle =  [UIBezierPath bezierPathWithOvalInRect:temp.mapBtnFrame];
    UIBezierPath *endCycle =  [UIBezierPath bezierPathWithOvalInRect:CGRectMake(0, 0, 0, 0)];
    //創建CAShapeLayer進行遮蓋
    CAShapeLayer *maskLayer = [CAShapeLayer layer];
    maskLayer.fillColor = [UIColor greenColor].CGColor;
    maskLayer.path = endCycle.CGPath;
    fromVC.view.layer.mask = maskLayer;
    //創建路徑動畫
    CABasicAnimation *maskLayerAnimation = [CABasicAnimation animationWithKeyPath:@"path"];
    maskLayerAnimation.delegate = self;
    maskLayerAnimation.fromValue = (__bridge id)(startCycle.CGPath);
    maskLayerAnimation.toValue = (__bridge id)((endCycle.CGPath));
    maskLayerAnimation.duration = [self transitionDuration:transitionContext];
    maskLayerAnimation.delegate = self;
    maskLayerAnimation.timingFunction = [CAMediaTimingFunction  functionWithName:kCAMediaTimingFunctionEaseInEaseOut];
    [maskLayerAnimation setValue:transitionContext forKey:@"transitionContext"];
    [maskLayer addAnimation:maskLayerAnimation forKey:@"path"];
}

- (void)presentAnimation:(id)transitionContext{
    UIViewController *toVC = [transitionContext viewControllerForKey:UITransitionContextToViewControllerKey];
    UIView *containerView = [transitionContext containerView];
    [containerView addSubview:toVC.view];
    //畫兩個圓路徑
//    UIBezierPath *startCycle =  [UIBezierPath bezierPathWithOvalInRect:fromVC.mapBtnFrame];
    UIBezierPath *startCycle =  [UIBezierPath bezierPathWithOvalInRect:CGRectMake(0, 0, 0, 0)];
    CGFloat x = MAX(100, containerView.frame.size.width - 100);
    CGFloat y = MAX(100, containerView.frame.size.height - 100);
    CGFloat radius = sqrtf(pow(x, 2) + pow(y, 2));
    UIBezierPath *endCycle = [UIBezierPath bezierPathWithArcCenter:containerView.center radius:radius startAngle:0 endAngle:M_PI * 2 clockwise:YES];
    //創建CAShapeLayer進行遮蓋
    CAShapeLayer *maskLayer = [CAShapeLayer layer];
    maskLayer.path = endCycle.CGPath;
    //將maskLayer作為toVC.View的遮蓋
    toVC.view.layer.mask = maskLayer;

    //創建路徑動畫
    CABasicAnimation *maskLayerAnimation = [CABasicAnimation animationWithKeyPath:@"path"];
    maskLayerAnimation.delegate = self;
    //動畫是加到layer上的，所以必須為CGPath，再將CGPath橋接為OC對象
    maskLayerAnimation.fromValue = (__bridge id)(startCycle.CGPath);
    maskLayerAnimation.toValue = (__bridge id)((endCycle.CGPath));
    maskLayerAnimation.duration = [self transitionDuration:transitionContext];
    maskLayerAnimation.delegate = self;
    maskLayerAnimation.timingFunction = [CAMediaTimingFunction  functionWithName:kCAMediaTimingFunctionEaseInEaseOut];

    [maskLayerAnimation setValue:transitionContext forKey:@"transitionContext"];
    [maskLayer addAnimation:maskLayerAnimation forKey:@"path"];
}

- (void)animationDidStop:(CAAnimation *)anim finished:(BOOL)flag{
    switch (_type) {
        case XWCircleSpreadTransitionTypePush:{
            id transitionContext = [anim valueForKey:@"transitionContext"];
            [transitionContext completeTransition:YES];
            UIView *toView = [transitionContext viewForKey:UITransitionContextToViewKey];
            toView.layer.mask = nil;
            UIViewController *vc = [transitionContext viewControllerForKey:UITransitionContextToViewControllerKey];
            vc.view.layer.mask = nil;
        }
            break;
        case XWCircleSpreadTransitionTypePop:{
            id transitionContext = [anim valueForKey:@"transitionContext"];
            [transitionContext completeTransition:YES];
            UIViewController *vc = [transitionContext viewControllerForKey:UITransitionContextFromViewControllerKey];
            vc.view.layer.mask = nil;
        }
            break;
    }
}
@end

剩下的就是在ViewControllerA中實現代理中的animationControllerForOperation：

#pragma mark -
#pragma mark - UINavigation Delegate
-(id)navigationController:(UINavigationController *)navigationController animationControllerForOperation:(UINavigationControllerOperation)operation fromViewController:(UIViewController *)fromVC toViewController:(UIViewController *)toVC
{

    if (fromVC == self) {
        return [XWCircleSpreadTransition transitionWithTransitionType:XWCircleSpreadTransitionTypePush];
    }
    if (toVC == self) {
        return [XWCircleSpreadTransition transitionWithTransitionType:XWCircleSpreadTransitionTypePop];
    }
    return nil;
}

到此，這個簡單的轉場動畫已經實現完畢，而且動畫效果可以自定義成自己想要的展現形式。

文章轉自 檸檬跑步的簡書