Ios 为什么不'；这些约束不起作用吗？

我正在以编程方式对UIView中的三个视图设置以下约束：

UIView *view1 = ((UIViewController *)[self.viewControllers objectAtIndex:0]).view;
UIView *view2 = ((UIViewController *)[self.viewControllers objectAtIndex:1]).view;
UIView *view3 = ((UIViewController *)[self.viewControllers objectAtIndex:2]).view;

NSDictionary *viewsDictionary = NSDictionaryOfVariableBindings(view1, view2, view3);
[self.contentView addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"H:|-0-[view1(==320)]-0-[view2(==320)]-0-[view3(==320)]|" options:0 metrics:0 views:viewsDictionary]];

我的意图是，每个视图都是320px宽的，彼此齐平，没有间隙，并且一个视图对着视图的左边缘

但是，在编译时，这些视图被放置在彼此的顶部，我在控制台中看到以下内容：

Unable to simultaneously satisfy constraints.
    Probably at least one of the constraints in the following list is one you don't want. Try this: (1) look at each constraint and try to figure out which you don't expect; (2) find the code that added the unwanted constraint or constraints and fix it. (Note: If you're seeing NSAutoresizingMaskLayoutConstraints that you don't understand, refer to the documentation for the UIView property translatesAutoresizingMaskIntoConstraints) 
(
    "<NSLayoutConstraint:0x211811c0 H:|-(0)-[UIView:0xc683790]   (Names: '|':UIView:0xc683320 )>",
    "<NSAutoresizingMaskLayoutConstraint:0x21179820 h=-&- v=-&- UIView:0xc683790.midX == UIView:0xc683320.midX - 340>",
    "<NSLayoutConstraint:0x211793d0 H:[UIView:0xc6a50c0]-(0)-|   (Names: '|':UIView:0xc683320 )>",
    "<NSLayoutConstraint:0x21179390 H:[UIView:0xc6a50c0(320)]>",
    "<NSLayoutConstraint:0x21179350 H:[UIView:0xc6a05f0]-(0)-[UIView:0xc6a50c0]>",
    "<NSLayoutConstraint:0x211563d0 H:[UIView:0xc6a05f0(320)]>",
    "<NSLayoutConstraint:0x21156390 H:[UIView:0xc683790]-(0)-[UIView:0xc6a05f0]>"
)

Will attempt to recover by breaking constraint 
<NSLayoutConstraint:0x21179350 H:[UIView:0xc6a05f0]-(0)-[UIView:0xc6a50c0]>

无法同时满足约束。
可能下面列表中至少有一个约束是您不想要的。试着这样做：（1）看看每个约束，试着找出你不期望的约束；（2） 找到添加了不需要的约束的代码，然后修复它。（注意：如果您看到不理解的NSAutoresizingMaskLayoutConstraints，请参阅UIView属性TranslatesAutoResizingMaskToConstraints的文档）
(
"",
"",
"",
"",
"",
"",
""
)
将尝试通过打破约束进行恢复

尝试设置

[view setTranslatesAutoresizingMaskIntoConstraints:NO];

对于你所有的观点，这通常足以解决这类问题