ios - 如何在 Ios 中使用自动布局制作垂直间距黑白 UIFields

Question

嗨，我是 iOS 的新手，在我的应用程序中，我使用的是自动布局视觉格式

但是我怎样才能在不同的条件下改变垂直间距

为此我使用了下面的代码，但垂直间距没有设置黑白 UIfields

请看我在此处给出的屏幕下方垂直空间“15”，但它不适用

我的代码:-

- (void)viewDidLoad {
    [super viewDidLoad];

 NSDictionary * views1 = NSDictionaryOfVariableBindings(RoundTripLabel,RoundTripDateTextField,RoundTripButton,BottomLabel1,BottomLabel2);


//Appying Horizental contstraints:-

    [MainScrollView addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"H:|-8-[RoundTripLabel]-8-|" options:0 metrics:nil views:views1]];

    [MainScrollView addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"H:|-8-[RoundTripDateTextField]-8-[RoundTripButton(30)]-|" options:0 metrics:nil views:views1]];

    [MainScrollView addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"H:|-8-[BottomLabel1]-8-|" options:0 metrics:nil views:views1]];

    [MainScrollView addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"H:|-8-[BottomLabel2]-8-|" options:0 metrics:nil views:views1]];


    //Appying Vertical contstraints:-

    [MainScrollView addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"V:|-100-[RoundTripLabel(17)]-10-[RoundTripDateTextField]-0-[BottomLabel1(17)]-10-[BottomLabel2(17)]" options:0 metrics:nil views:views1]];

     NSDictionary * views2 = NSDictionaryOfVariableBindings(RoundTripLabel,RoundTripButton);

    [MainScrollView addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"V:[RoundTripLabel]-10-[RoundTripButton]" options:0 metrics:nil views:views2]];


    //Defining  Heights Using Constraint With Item Formate:-

    RoundTripDateTextFieldHeight = [NSLayoutConstraint constraintWithItem:RoundTripDateTextField attribute:NSLayoutAttributeHeight relatedBy:NSLayoutRelationEqual toItem:nil attribute:NSLayoutAttributeNotAnAttribute multiplier:1.0f constant:30.0f];
    [MainScrollView addConstraint:RoundTripDateTextFieldHeight];

    RoundTripButtonHeight = [NSLayoutConstraint constraintWithItem:RoundTripButton attribute:NSLayoutAttributeHeight relatedBy:NSLayoutRelationEqual toItem:nil attribute:NSLayoutAttributeNotAnAttribute multiplier:1.0f constant:30.0f];
    [MainScrollView addConstraint:RoundTripButtonHeight];

    VerticalSpacing = [NSLayoutConstraint constraintWithItem:BottomLabel1 attribute:NSLayoutAttributeTop relatedBy:NSLayoutRelationEqual toItem:RoundTripDateTextField attribute:NSLayoutAttributeBottom multiplier:1.0f constant:15.0f];
    [MainScrollView addConstraint:RoundTripDateTextFieldHeight];

    [MainScrollView setNeedsDisplay];

}

Answer 1

在您的代码中，这些约束存在问题

第一个约束:

无需再次添加 RoundTripDateTextFieldHeight，您需要添加 VerticalSpacing

VerticalSpacing = [NSLayoutConstraint constraintWithItem:BottomLabel1 attribute:NSLayoutAttributeTop relatedBy:NSLayoutRelationEqual toItem:RoundTripDateTextField attribute:NSLayoutAttributeBottom multiplier:1.0f constant:15.0f];
[MainScrollView addConstraint:VerticalSpacing];  // instead of [MainScrollView addConstraint:RoundTripDateTextFieldHeight];

第二

在两个标签之间添加垂直间距

NSLayoutConstraint *VerticalSpacingLbl2 = [NSLayoutConstraint constraintWithItem:BottomLabel2 attribute:NSLayoutAttributeTop relatedBy:NSLayoutRelationEqual toItem:BottomLabel1 attribute:NSLayoutAttributeBottom multiplier:1.0f constant:10.0f];
[MainScrollView addConstraint:VerticalSpacingLbl2];  

第三

在限制条件下改变

  //Appying Vertical contstraints:-

  [MainScrollView addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"V:|-100-[RoundTripLabel(17)]-10-[RoundTripDateTextField]-0-[BottomLabel1(17)]-10-[BottomLabel2(17)]" options:0 metrics:nil views:views1]];

有了这个

 [MainScrollView addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"V:|-100-[RoundTripLabel(17)]-10-[RoundTripDateTextField]" options:0 metrics:nil views:views1]];