自动布局约束警告“将尝试通过打破约束来恢复"

Autolayout constraints warning quot;Will attempt to recover by breaking constraintquot;(自动布局约束警告“将尝试通过打破约束来恢复)

问题描述

当应用程序在此设备上运行时，我正在为 iPhone 4 设置一些具体限制.就对齐和一切而言，一切看起来都很棒.

I am setting some specifics constraints for iPhone 4 when the app is ran on this device. Everything look great in terms of alignment and everything.

但是，我的所有约束都出现了错误，我试图通过打破约束来恢复它们.

But, I am getting an error for all my constraints that is trying to recover them by breaking the constraints.

当它检测到它是否是 iPhone 4 时，在我的 viewDidLoad 中调用此方法

This method gets call in my viewDidLoad when it detects if its an iPhone 4

- (void) addConstraints {

    // removing automatic system constraints
    [self.view removeConstraints:self.view.constraints];
    [self.view setTranslatesAutoresizingMaskIntoConstraints:NO];


    NSDictionary *views = NSDictionaryOfVariableBindings(appBackground, myCustomer, myItemDetails, myItemQuantity, myItemPrice, myNext, myBtn); // UIImageView, UITextField, UIButton

    for (UIView *view in [views allValues]) {
        view.translatesAutoresizingMaskIntoConstraints = NO;
    }

    NSDictionary *metrics = @{@"width": @210.0, @"height": @42.0, @"verticalSpacing": @34};

    NSArray *constraints = [NSLayoutConstraint constraintsWithVisualFormat:@"V:|[appBackground]|"
                                                                   options:0
                                                                   metrics:nil
                                                                     views:views];

    constraints = [constraints arrayByAddingObjectsFromArray:[NSLayoutConstraint constraintsWithVisualFormat:@"H:|[appBackground]|"
                                                                   options:0
                                                                   metrics:nil
                                                                     views:views]];

    constraints = [constraints arrayByAddingObjectsFromArray:[NSLayoutConstraint constraintsWithVisualFormat:@"V:|-(85)-[myCustomer(==height)]-(verticalSpacing)-[myItemDetails(==height)]-(verticalSpacing)-[myItemQuantity(==height)]-(verticalSpacing)-[myItemPrice(==height)]-(18)-[myNext(==35)]-(71.5)-[myBtn(==50)]-(7.5)-|"
                                                                    options:0
                                                                    metrics:metrics
                                                                      views:views]];

    constraints = [constraints arrayByAddingObjectsFromArray:[NSLayoutConstraint constraintsWithVisualFormat:@"H:|-50-[myCustomer(==width)]-|"
                                                                                                     options:0
                                                                                                     metrics:metrics
                                                                                                       views:views]];

    constraints = [constraints arrayByAddingObjectsFromArray:[NSLayoutConstraint constraintsWithVisualFormat:@"H:|-50-[myItemDetails(==width)]-|"
                                                                                                     options:0
                                                                                                     metrics:metrics
                                                                                                       views:views]];

    constraints = [constraints arrayByAddingObjectsFromArray:[NSLayoutConstraint constraintsWithVisualFormat:@"H:|-50-[myItemQuantity(==width)]-|"
                                                                                                     options:0
                                                                                                     metrics:metrics
                                                                                                       views:views]];

    constraints = [constraints arrayByAddingObjectsFromArray:[NSLayoutConstraint constraintsWithVisualFormat:@"H:|-50-[myItemPrice(==width)]-|"
                                                                                                     options:0
                                                                                                     metrics:metrics
                                                                                                       views:views]];

    constraints = [constraints arrayByAddingObjectsFromArray:[NSLayoutConstraint constraintsWithVisualFormat:@"H:|-78-[myNext(==173)]-|"
                                                                                                     options:0
                                                                                                     metrics:metrics
                                                                                                       views:views]];

    constraints = [constraints arrayByAddingObjectsFromArray:[NSLayoutConstraint constraintsWithVisualFormat:@"H:|-11.5-[myBtn(==54)]-|"
                                                                                                     options:0
                                                                                                     metrics:metrics
                                                                                                       views:views]];

    [self.view addConstraints:constraints];

}

错误！

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:0xb8282f0 H:|-(50)-[UITextField:0xb823fc0]   (Names: '|':UIView:0xb82f360 )>",
    "<NSLayoutConstraint:0xb828320 H:[UITextField:0xb823fc0(210)]>",
    "<NSLayoutConstraint:0xb82be10 H:[UITextField:0xb823fc0]-(NSSpace(20))-|   (Names: '|':UIView:0xb82f360 )>",
    "<NSLayoutConstraint:0xb82d3d0 H:|-(78)-[UIButton:0xb82ad50]   (Names: '|':UIView:0xb82f360 )>",
    "<NSLayoutConstraint:0xb82d420 H:[UIButton:0xb82ad50(173)]>",
    "<NSLayoutConstraint:0xb82d450 H:[UIButton:0xb82ad50]-(NSSpace(20))-|   (Names: '|':UIView:0xb82f360 )>"
)

Will attempt to recover by breaking constraint 
<NSLayoutConstraint:0xb82d450 H:[UIButton:0xb82ad50]-(NSSpace(20))-|   (Names: '|':UIView:0xb82f360 )>

Break on objc_exception_throw to catch this in the debugger.
The methods in the UIConstraintBasedLayoutDebugging category on UIView listed in <UIKit/UIView.h> may also be helpful.
2014-08-03 14:03:29.239 iReceipt[2886:607] 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:0xb8282f0 H:|-(50)-[UITextField:0xb823fc0]   (Names: '|':UIView:0xb82f360 )>",
    "<NSLayoutConstraint:0xb828320 H:[UITextField:0xb823fc0(210)]>",
    "<NSLayoutConstraint:0xb82be10 H:[UITextField:0xb823fc0]-(NSSpace(20))-|   (Names: '|':UIView:0xb82f360 )>",
    "<NSLayoutConstraint:0xb82d480 H:|-(11.5)-[UIButton:0xb820120]   (Names: '|':UIView:0xb82f360 )>",
    "<NSLayoutConstraint:0xb82e390 H:[UIButton:0xb820120(54)]>",
    "<NSLayoutConstraint:0xb82e3c0 H:[UIButton:0xb820120]-(NSSpace(20))-|   (Names: '|':UIView:0xb82f360 )>"
)

Will attempt to recover by breaking constraint 
<NSLayoutConstraint:0xb82e3c0 H:[UIButton:0xb820120]-(NSSpace(20))-|   (Names: '|':UIView:0xb82f360 )>

如果你们需要更多信息，请告诉我..

Please let me know if you guys need more information..

推荐答案

这三个约束:

"<NSLayoutConstraint:0xb8282f0 H:|-(50)-[UITextField:0xb823fc0]   (Names: '|':UIView:0xb82f360 )>",
"<NSLayoutConstraint:0xb828320 H:[UITextField:0xb823fc0(210)]>",
"<NSLayoutConstraint:0xb82be10 H:[UITextField:0xb823fc0]-(NSSpace(20))-|   (Names: '|':UIView:0xb82f360 )>",

规定超级视图为 50 + 210 + 20 == 280 点宽.

dictate that the superview be 50 + 210 + 20 == 280 points wide.

这三个约束:

"<NSLayoutConstraint:0xb82d3d0 H:|-(78)-[UIButton:0xb82ad50]   (Names: '|':UIView:0xb82f360 )>",
"<NSLayoutConstraint:0xb82d420 H:[UIButton:0xb82ad50(173)]>",
"<NSLayoutConstraint:0xb82d450 H:[UIButton:0xb82ad50]-(NSSpace(20))-|   (Names: '|':UIView:0xb82f360 )>"

规定同一个超级视图为 78 + 173 + 20 == 271 点宽.

dictate that the same superview be 78 + 173 + 20 == 271 points wide.

显然，这两者不可能同时为真.你需要决定你真正想要在这里发生的事情.我们无法读懂你的想法，UIKit 也一样.

Obviously, those can't both be true at the same time. You need to decide what you really want to happen here. We can't read your mind and neither can UIKit.

通常，您不会在按钮上设置宽度限制；您让它使用其固有大小和适当的优先级来实现内容拥抱和抗压缩性.此外，您可能不希望在按钮的任一侧设置硬间距.要么让该间距不受约束地变化，因此按钮可以是其固有大小，降低该约束的优先级使其成为可选的，或者进行不等式以便您具有最小间距但不是精确间距.

Usually, you don't set a width constraint on a button; you let it use its intrinsic size with appropriate priorities for content hugging and compression resistance. Also, you may not wish to set hard spacing on either side of the button. Either let that spacing vary without constraint so the button can be its intrinsic size, lower the priority of that constraint so it's optional, or make an inequality so you have a minimum spacing but not an exact spacing.

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