如何使用NSLayoutConstraint限制UIButton高度

我有UItoolbar其中增加了兩項1. UITextView和2. UIButton。 UITextview的屬性是根據輸入的文本自動生長。雖然UITextview高度的增長，我想限制UIButton高度，即UIButton高度不應該增加。如何使用NSLayoutConstraint限制UIButton高度

[_toolbar setItems:[NSArray arrayWithObjects:barButtonItemCommentText,barButtonItemSubmit,nil]]; 
submitBtn.translatesAutoresizingMaskIntoConstraints = NO; 
textView.translatesAutoresizingMaskIntoConstraints = NO; 
_toolbar.translatesAutoresizingMaskIntoConstraints = NO; 

[_toolbar addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"H:|-8-[textView]-79-|" options:0 metrics:nil views:NSDictionaryOfVariableBindings(textView)]]; 

[_toolbar addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"V:|-8-[textView]-8-|" options:0 metrics:nil views:NSDictionaryOfVariableBindings(textView)]]; 

[_toolbar addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"H:|-[submitBtn]-8-|" options:0 metrics:nil views:NSDictionaryOfVariableBindings(submitBtn)]]; 


[_toolbar addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"V:|-8-[submitBtn]-8-|" options:NSLayoutFormatAlignAllBaseline metrics:nil views:NSDictionaryOfVariableBindings(submitBtn)]]; 

[_toolbar addConstraint:[NSLayoutConstraint constraintWithItem:submitBtn 
               attribute:NSLayoutAttributeWidth 
               relatedBy:NSLayoutRelationEqual 
                toItem:nil 
               attribute:NSLayoutAttributeNotAnAttribute 
               multiplier:1.0 
                constant:60]]; 
[textView setContentCompressionResistancePriority:UILayoutPriorityRequired forAxis:UILayoutConstraintAxisHorizontal]; 
[textView setContentCompressionResistancePriority:UILayoutPriorityRequired forAxis:UILayoutConstraintAxisVertical]; 

[_toolbar setContentCompressionResistancePriority:UILayoutPriorityRequired forAxis:UILayoutConstraintAxisVertical]; 


[_toolbar addConstraint:[NSLayoutConstraint constraintWithItem:_toolbar attribute:NSLayoutAttributeHeight relatedBy:NSLayoutRelationLessThanOrEqual toItem:nil attribute:NSLayoutAttributeNotAnAttribute multiplier:1.0f constant:MaxToolbarHeight]];

爲了參考，見附圖屏幕截圖：

來源

2016-02-11 Sachin Kumaram

的高度可能改變這一行'[_toolbar addConstraints：[NSLayoutConstraint constraintsWithVisualFormat：@ 「V：| -8- [submitBtn] -8- |」 options：NSLayoutFormatAlignAllBaseline metrics：nil views：NSDictionaryOfVariableBindings（submitBtn）]];'to this'[_toolbar addConstraints：[NSLayoutConstraint constraintsWithVisualFormat：@「V：| - > = 8- [submitBtn] -8- |」選項：NSLayoutFormatAlignAllBaseline指標：無視圖：NSDictionaryOfVariableBindings（submitBtn）]];' –

非常感謝@迪瑪，你已經使我的一天:) –

下面提到的約束使得它在垂直方向伸展，因爲它要求從頂部和底部總是8像素。

[_toolbar addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"V:|-8-[submitBtn]-8-|" options:NSLayoutFormatAlignAllBaseline metrics:nil views:NSDictionaryOfVariableBindings(submitBtn)]];

如果將其更改到一定的高度比它不會垂直增長，在這種情況下總是24.

[_toolbar addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"V:[submitBtn(24)]-8-|" options:NSLayoutFormatAlignAllBaseline metrics:nil views:NSDictionaryOfVariableBindings(submitBtn)]];

來源

2016-02-11 13:30:05 Gandalf

我發現在我的問題和你的答案評論的答案是作品完美。感謝甘道夫和迪馬。 –

如何使用NSLayoutConstraint限制UIButton高度

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