当我在此设备上运行该应用时，我正在为iPhone 4设置一些细节限制。在对齐和一切方面，一切看起来都很棒。
但是，我正在试图通过打破约束来试图恢复它们。
这个方法在检测到它是否是iPhone 4
时会在我的viewDidLoad中调用- (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。
答案 0 :(得分：19)
这三个限制因素：
"<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。
这三个限制因素：
"<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 )>"
指示相同的超级视图为78 + 173 + 20 == 271点宽。
显然，那些不可能同时是真的。你需要决定你真正想要在这里发生什么。我们无法读懂你的想法，UIKit也无法读懂。通常，您不要在按钮上设置宽度约束;你让它使用它的内在大小和适当的内容拥抱和抗压性优先级。此外，您可能不希望在按钮的任一侧设置硬间距。要么让间距在没有约束的情况下变化，那么按钮可以是它的内在大小，降低该约束的优先级，因此它是可选的，或者使不等式成为最小间距但不是精确间距。
答案 1 :(得分：3)
您过多地限制了自己的观点。你必须总是留下例如leftmargin，width和rightmargin灵活的一个，并让autolayout引擎拉伸那个。
没有任何数字的单个短划线表示默认距离，即20像素。因此，如果您删除
上的尾随约束@"H:|-78-[myNext(==173)]-|"
@"H:|-11.5-[myBtn(==54)]-|"
并将其更改为
@"H:|-78-[myNext(==173)]"
@"H:|-11.5-[myBtn(==54)]"
就个人而言，我从不使用标准API：s进行自动布局。我使用了库PureLayout，它精彩地抽象了autolayout！