Ios 以编程方式使用约束设置UIImageView（视图）从点A到点B的动画

我有一个图像视图，我已经在屏幕的右中对齐了。添加带有约束的图像视图本身时，一切正常。我需要设置从原始位置（点A）到屏幕底部（点B）的图像视图的动画；问题是，当我尝试从点A到点B设置动画时，图像视图从屏幕的左上角开始，就像它只是在没有约束的情况下添加的一样（与我希望从中心开始的位置相反）

以下是代码和一些注释：

#define DEGREES_TO_RADIANS(x) (M_PI * x / 180.0) //defined above
- (void)viewDidLoad
{
UIImage *cardFaceDownImage = [UIImage imageNamed:@"b-top@2x.png"];
UIImageView *dealCardDown = [[UIImageView alloc] initWithImage:cardFaceDownImage];
dealCardDown.translatesAutoresizingMaskIntoConstraints = NO;

NSLayoutConstraint *dealCardConstraintY = [NSLayoutConstraint constraintWithItem:dealCardDown attribute:NSLayoutAttributeCenterY relatedBy:NSLayoutRelationEqual toItem:self.view attribute:NSLayoutAttributeCenterY multiplier:1 constant:1];

NSLayoutConstraint *dealCardConstraintX = [NSLayoutConstraint constraintWithItem:dealCardDown attribute:NSLayoutAttributeCenterX relatedBy:NSLayoutRelationEqual toItem:self.view attribute:NSLayoutAttributeCenterX multiplier:1 constant:130];

[self.view addConstraint:dealCardConstraintY];
[self.view addConstraint:dealCardConstraintX];
[self.view addSubview:dealCardDown];

//IF I comment out the below code the UIImageView lines up where I want it (Point A)
//IF I don't coment it out, the imageview starts in the upper left hand corner of the screen
//where it normally would as if just adding an image view programatically without
//constraints would, but it does end up where I want it to (Point B)

[self.view removeConstraint:dealCardConstraintX];
[self.view removeConstraint:dealCardConstraintY];

dealCardConstraintY = [NSLayoutConstraint constraintWithItem:dealCardDown attribute:NSLayoutAttributeCenterY relatedBy:NSLayoutRelationEqual toItem:self.view attribute:NSLayoutAttributeBottom multiplier:1 constant:1];

dealCardConstraintX = [NSLayoutConstraint constraintWithItem:dealCardDown attribute:NSLayoutAttributeCenterX relatedBy:NSLayoutRelationEqual toItem:self.view attribute:NSLayoutAttributeLeft multiplier:1 constant:130];

[self.view addConstraint:dealCardConstraintY];
[self.view addConstraint:dealCardConstraintX];

[self.view setNeedsUpdateConstraints];

[UIView animateWithDuration:2.0 delay:2.0 options:UIViewAnimationCurveEaseIn animations:^(void)
 {
     dealCardDown.transform = CGAffineTransformRotate(dealCardDown.transform, DEGREES_TO_RADIANS(90));

     [self.view layoutIfNeeded];

 }
 completion:^(BOOL finished)
 { 
 }
 ];
 }

---

..

您需要将约束的更改移动到动画块中，以便正确设置动画。 这个代码对我很有用

- (void)viewDidAppear:(BOOL)animated
{
[super viewDidAppear:animated];

UIView *dealCardDown = [[UIView alloc] initWithFrame:(CGRect){0,0,50,50}];
dealCardDown.backgroundColor = [UIColor redColor];
dealCardDown.translatesAutoresizingMaskIntoConstraints = NO;
NSLayoutConstraint *sizeConstraint = [NSLayoutConstraint constraintWithItem: dealCardDown attribute: NSLayoutAttributeWidth relatedBy: NSLayoutRelationEqual toItem: nil attribute:NSLayoutAttributeNotAnAttribute multiplier: 1 constant: 50];
[dealCardDown addConstraint:sizeConstraint];
sizeConstraint = [NSLayoutConstraint constraintWithItem: dealCardDown attribute: NSLayoutAttributeHeight relatedBy: NSLayoutRelationEqual toItem: nil attribute:NSLayoutAttributeNotAnAttribute multiplier: 1 constant: 50];
[dealCardDown addConstraint:sizeConstraint];
[self.view addSubview:dealCardDown];

NSLayoutConstraint *dealCardConstraintX = [NSLayoutConstraint constraintWithItem:dealCardDown attribute:NSLayoutAttributeCenterX relatedBy:NSLayoutRelationEqual toItem:self.view attribute:NSLayoutAttributeCenterX multiplier:1.f constant:0.f];
NSLayoutConstraint *dealCardConstraintY = [NSLayoutConstraint constraintWithItem:dealCardDown attribute:NSLayoutAttributeBottom relatedBy:NSLayoutRelationEqual toItem:self.view attribute:NSLayoutAttributeBottom multiplier:1.f constant:-self.view.center.y+dealCardDown.frame.size.height/2];


[self.view addConstraint:dealCardConstraintX];
[self.view addConstraint:dealCardConstraintY];
[self.view layoutIfNeeded];

[UIView animateWithDuration:2.0 delay:0.0 options:UIViewAnimationCurveEaseIn animations:^(void)
 {
     dealCardDown.transform = CGAffineTransformRotate(dealCardDown.transform, 90*M_PI/180);
     dealCardConstraintY.constant = 0;
     [self.view layoutIfNeeded];

 }
                 completion:^(BOOL finished)
 { 
 }
 ];
}

---

我只是复制并粘贴了这段代码。它为我做的只是在屏幕的右侧放一个小的（50,50）红色视图。CGAffineTransformRotate可以工作（正如我的代码中所做的那样），我可能应该将其从示例中删除，但我需要视图从屏幕的中心移动到底部。谢谢你！谢谢你的帮助，等等。它实际上是把它推到右边，然后制作动画。我会按照你想要的方式调整它。给我一秒钟：）它不会立即开始动画，因为您的代码示例中有2.0延迟。它也有这种奇怪的定位，因为在您的示例中，中心偏移量为130。我更新了代码示例，使其从中间移动到底部。享受：）总结一下。它在viewDidLoad中不起作用，因为在应用自动布局之前调用了此方法。要使其工作，您需要将代码移动到生命周期中进一步执行的某个方法，例如-（void）viewDidAppear:（BOOL）animated