如何在IOS中逐个设置约束动画？

我有6种观点。我想一个接一个地设置约束的动画，也就是说，我只需要在第一个视图之后的第二个视图上设置动画，然后在第二个视图之后设置第三个，依此类推。我已经在动画的完成处理程序中添加了代码，但它不起作用。在情节提要中，所有约束的初始值都设置为300。我想逐一将其更改为0。现在，只有第一个动画正在工作。这就是我所做的

layoutTopFirst.constant = 0.0;
    [UIView animateWithDuration:1.0 animations:^{
        [self.view layoutIfNeeded];
    } completion:^(BOOL finished) {
        self->layoutTopSecond.constant = 0.0;
        [UIView animateWithDuration:1.0 animations:^{
            [self.view layoutIfNeeded];
        } completion:^(BOOL finished) {
            self->layoutTopThird.constant = 0.0;
            [UIView animateWithDuration:1.0 animations:^{
                [self.view layoutIfNeeded];
            } completion:^(BOOL finished) {
                self->layoutTopFourth.constant = 0.0;
                [UIView animateWithDuration:1.0 animations:^{
                    [self.view layoutIfNeeded];
                } completion:^(BOOL finished) {
                    self->layoutTopFifth.constant = 0.0;
                    [UIView animateWithDuration:1.0 animations:^{
                        [self.view layoutIfNeeded];
                    } completion:^(BOOL finished) {
                        self->layoutTopSixth.constant = 0.0;
                        [UIView animateWithDuration:1.0 animations:^{
                            [self.view layoutIfNeeded];
                        } completion:^(BOOL finished) {
                            
                        }];
                    }];
                }];
            }];
        }];
    }];

---

如何一个接一个地制作动画？

如果您显示所有代码（如何设置约束等），这会有所帮助

但是，这里有一个简单的例子

它创建6个标签，顶部约束为100。点击“制作动画”按钮，将动画设置到顶部：0.0。。。再次轻按可将动画设置回100：

#import "SequentialAnimViewController.h"

@interface SequentialAnimViewController () {
    NSMutableArray *views;
    NSMutableArray *topConstraints;
}
@end

@implementation SequentialAnimViewController

- (void)viewDidLoad {
    [super viewDidLoad];

    UIButton *button = [UIButton buttonWithType:UIButtonTypeSystem];
    [button addTarget:self action:@selector(animViews) forControlEvents:UIControlEventTouchUpInside];
    [button setTitle:@"Do Anim" forState:UIControlStateNormal];
    button.backgroundColor = [UIColor colorWithWhite:0.9 alpha:1.0];
    button.translatesAutoresizingMaskIntoConstraints = NO;
    [self.view addSubview:button];
    
    [button.centerXAnchor constraintEqualToAnchor:[self.view centerXAnchor]].active = YES;
    [button.centerYAnchor constraintEqualToAnchor:[self.view centerYAnchor]].active = YES;
    [button.widthAnchor constraintEqualToConstant:200.0].active = YES;

    views = [NSMutableArray new];
    topConstraints = [NSMutableArray new];
    
    CGFloat x = 40.0;
    CGFloat w = 40.0;

    UILayoutGuide *g = [self.view safeAreaLayoutGuide];

    for (int i = 0; i < 6; i++) {
        UILabel *v = [UILabel new];
        v.backgroundColor = [UIColor blueColor];
        v.textColor = [UIColor yellowColor];
        v.textAlignment = NSTextAlignmentCenter;
        v.text = [NSString stringWithFormat:@"%i", i];
        v.translatesAutoresizingMaskIntoConstraints = NO;

        [self.view addSubview:v];
        [v.widthAnchor constraintEqualToConstant:w].active = YES;
        [v.heightAnchor constraintEqualToConstant:w].active = YES;
        [v.leadingAnchor constraintEqualToAnchor:g.leadingAnchor constant:x].active = YES;

        [topConstraints addObject:[v.topAnchor constraintEqualToAnchor:g.topAnchor constant:100.0]];
        [views addObject:v];

        x += w + 8;
    }
    
    [NSLayoutConstraint activateConstraints:topConstraints];
}

-(void)animViews {
    __block int i = 0;
    __block CGFloat newConstant = ((NSLayoutConstraint *)self->topConstraints[0]).constant == 0.0 ? 100.0 : 0.0;
    ((NSLayoutConstraint *)self->topConstraints[i++]).constant = newConstant;
    [UIView animateWithDuration:1.0 animations:^{
        [self.view layoutIfNeeded];
    } completion:^(BOOL finished) {
        ((NSLayoutConstraint *)self->topConstraints[i++]).constant = newConstant;
        [UIView animateWithDuration:1.0 animations:^{
            [self.view layoutIfNeeded];
        } completion:^(BOOL finished) {
            ((NSLayoutConstraint *)self->topConstraints[i++]).constant = newConstant;
            [UIView animateWithDuration:1.0 animations:^{
                [self.view layoutIfNeeded];
            } completion:^(BOOL finished) {
                ((NSLayoutConstraint *)self->topConstraints[i++]).constant = newConstant;
                [UIView animateWithDuration:1.0 animations:^{
                    [self.view layoutIfNeeded];
                } completion:^(BOOL finished) {
                    ((NSLayoutConstraint *)self->topConstraints[i++]).constant = newConstant;
                    [UIView animateWithDuration:1.0 animations:^{
                        [self.view layoutIfNeeded];
                    } completion:^(BOOL finished) {
                        ((NSLayoutConstraint *)self->topConstraints[i++]).constant = newConstant;
                        [UIView animateWithDuration:1.0 animations:^{
                            [self.view layoutIfNeeded];
                        } completion:^(BOOL finished) {
                            NSLog(@"All Done!");
                        }];
                    }];
                }];
            }];
        }];
    }];
}
@end

#导入“SequentialAnimViewController.h”
@接口顺序视图控制器（）{
NSMutableArray*视图；
NSMUTABLEARRY*topConstraints；
}
@结束
@实现顺序视图控制器
-（无效）viewDidLoad{
[超级视图下载]；
UIButton*按钮=[UIButton按钮类型：UIButtonTypeSystem]；
[按钮添加目标：自我操作：@selector（AnimView）for ControlEvents:UIControlEventTouchUpInside]；
[按钮设置标题：@“执行动画”状态：uicontrol状态正常]；
button.backgroundColor=[UIColor colorWithWhite:0.9 alpha:1.0]；
button.translatesAutoresizingMaskIntoConstraints=否；
[self.view addSubview:按钮]；
[button.centerXAnchor constraintEqualToAnchor:[self.view centerXAnchor]]。active=是；
[button.centerYAnchor constraintEqualToAnchor:[self.view centerYAnchor]]。active=是；
[button.widthAnchor constraintEqualToConstant:200.0]。活动=是；
视图=[NSMUTABLEARRY new]；
topConstraints=[NSMutableArray new]；
CGX=40.0；
CGW=40.0；
UILayoutGuide*g=[self.view安全区域LayoutGuide]；
对于（int i=0；i<6；i++）{
UILabel*v=[UILabel new]；
v、 背景色=[UIColor blueColor]；
v、 textColor=[UIColor yellowColor]；
v、 textAlignment=NSTextAlignmentCenter；
v、 text=[NSString stringWithFormat:@“%i”，i]；
v、 translatesAutoresizingMaskIntoConstraints=否；
[self.view addSubview:v]；
[v.widthAnchor constraintEqualToConstant:w]。活动=是；
[v.heightAnchor constraintEqualToConstant:w]。活动=是；
[v.leadingAnchor constraintEqualToAnchor:g.leadingAnchor常量：x]。活动=是；
[topConstraints addObject:[v.topAnchor constraintEqualToAnchor:g.topAnchor常量：100.0]；
[视图添加对象：v]；
x+=w+8；
}
[NSLayoutConstraint activateConstraints:topConstraints]；
}
-（无效）视图{
__块int i=0；
__块CGFloat newConstant=（（NSLayoutConstraint*）self->topConstraints[0]）。constant==0.0？100.0:0.0；
（（NSLayoutConstraint*）self->topConstraints[i++]）。常量=新常量；
[UIView animateWithDuration:1.0动画：^{
[self.view layoutifneed]；
}完成：^（布尔完成）{
（（NSLayoutConstraint*）self->topConstraints[i++]）。常量=新常量；
[UIView animateWithDuration:1.0动画：^{
[self.view layoutifneed]；
}完成：^（布尔完成）{
（（NSLayoutConstraint*）self->topConstraints[i++]）。常量=新常量；
[UIView animateWithDuration:1.0动画：^{
[self.view layoutifneed]；
}完成：^（布尔完成）{
（（NSLayoutConstraint*）self->topConstraints[i++]）。常量=新常量；
[UIView animateWithDuration:1.0动画：^{
[self.view layoutifneed]；
}完成：^（布尔完成）{
（（NSLayoutConstraint*）self->topConstraints[i++]）。常量=新常量；
[UIView animateWithDuration:1.0动画：^{
[self.view layoutifneed]；
}完成：^（布尔完成）{
（（NSLayoutConstraint*）self->topConstraints[i++]）。常量=新常量；
[UIView animateWithDuration:1.0动画：^{
[self.view layoutifneed]；
}完成：^（布尔完成）{
NSLog（@“全部完成！”）；
}];
}];
}];
}];
}];
}];
}
@结束

如果只有第一个正在设置动画，请确保

• 其他五个约束引用都指向不同的垂直约束。。。例如，如果它们是

  nil

  ，则不会看到任何更改
• 他们都是活跃的
• 没有任何其他约束阻止更新的常量产生更改

---

对于它的价值，你可以考虑用关键帧动画消除你的完成处理塔，例如

CGFloat relativeDuration = 1.0 / 6.0;

[UIView animateKeyframesWithDuration:6 delay:0 options:kNilOptions animations:^{
    [UIView addKeyframeWithRelativeStartTime:0 relativeDuration:relativeDuration animations:^{
        self.topConstraint1.constant = 0;
        [self.view layoutIfNeeded];
    }];

    [UIView addKeyframeWithRelativeStartTime:1.0 * relativeDuration relativeDuration:relativeDuration animations:^{
        self.topConstraint2.constant = 0;
        [self.view layoutIfNeeded];
    }];

    [UIView addKeyframeWithRelativeStartTime:2.0 * relativeDuration relativeDuration:relativeDuration animations:^{
        self.topConstraint3.constant = 0;
        [self.view layoutIfNeeded];
    }];

    [UIView addKeyframeWithRelativeStartTime:3.0 * relativeDuration relativeDuration:relativeDuration animations:^{
        self.topConstraint4.constant = 0;
        [self.view layoutIfNeeded];
    }];

    [UIView addKeyframeWithRelativeStartTime:4.0 * relativeDuration relativeDuration:relativeDuration animations:^{
        self.topConstraint5.constant = 0;
        [self.view layoutIfNeeded];
    }];

    [UIView addKeyframeWithRelativeStartTime:5.0 * relativeDuration relativeDuration:relativeDuration animations:^{
        self.topConstraint6.constant = 0;
        [self.view layoutIfNeeded];
    }];
} completion:nil];

或者更简单一点：

NSArray <NSLayoutConstraint *> *constraints = @[self.topConstraint1, self.topConstraint2, self.topConstraint3, self.topConstraint4, self.topConstraint5, self.topConstraint6];

CGFloat relativeDuration = 1.0 / (CGFloat) constraints.count;

[UIView animateKeyframesWithDuration:totalDuration delay:0 options:kNilOptions animations:^{
    for (NSInteger i = 0; i < constraints.count; i++) {
        [UIView addKeyframeWithRelativeStartTime: ((CGFloat) i) * relativeDuration relativeDuration:relativeDuration animations:^{
            constraints[i].constant = 0;
            [self.view layoutIfNeeded];
        }];
    }
} completion:nil];

NSArray*constraints=@[self.topsconstraint1、self.topsconstraint2、self.topsconstraint3、self.topsconstraint4、self.topsconstraint5、self.topsconstraint6]；
CGFloat relativeDuration=1.0/（CGFloat）constraints.count；
[UIView animateKeyframesWithDuration:totalDuration延迟：0选项：针织动画：^{
对于（NSInteger i=0；i

这将产生：

---

“它不起作用”是以什么方式出现的？所有的动画都是一次完成的吗？没有动画吗？只有第一个动画吗？请详细说明我已经更新了这个问题。现在只有第一个正在制作动画。你能在每次完成时添加一个日志来查看发生了什么吗？注意，这并不是一个快速的话题，但没关系。这是否回答了你的问题