Ios 应用一些约束时，UITextfield将变得不可编辑

当我使用

UITextfield

、

UILabel

和

UIButton

时，发生了一些奇怪的事情。我正在应用约束，以便

标签

和

文本字段

集中在

ui视图

中。按钮钉在底部。当我运行此代码时，

UITextField

变得不可编辑。有人能告诉我下面的代码出了什么问题吗？

---

有时UILabel位于文本字段的顶部。也检查一下。你介意详细说明一下吗？谢谢

UIView* topLayout = [[UIView alloc]init];
[topLayout setTranslatesAutoresizingMaskIntoConstraints:NO];
topLayout.backgroundColor = [UIColor whiteColor];

[self.view addSubview: topLayout];

NSArray  *topLayoutHConstraints = [NSLayoutConstraint constraintsWithVisualFormat:@"H:[parentView(==mainView)]" options:0 metrics:0 views:@{@"parentView": topLayout, @"mainView":self.view}];
NSArray  *topLayoutVConstraints = [NSLayoutConstraint constraintsWithVisualFormat:@"V:|[parentView]|" options:0 metrics:0 views:@{@"parentView": topLayout}];
[self.view addConstraints:topLayoutHConstraints];
[self.view addConstraints:topLayoutVConstraints];

UIView *childViewLayout = [[UIView alloc]init];
childViewLayout.backgroundColor = [UIColor yellowColor];
[childViewLayout setTranslatesAutoresizingMaskIntoConstraints:NO];
[topLayout addSubview:childViewLayout];

NSLayoutConstraint  *childViewControlsHConstraints = [NSLayoutConstraint constraintWithItem:childViewLayout attribute:NSLayoutAttributeCenterX relatedBy:NSLayoutRelationEqual toItem:topLayout attribute:NSLayoutAttributeCenterX multiplier:1.0 constant:0.0];
NSLayoutConstraint  *childViewControlsVConstraints = [NSLayoutConstraint constraintWithItem:childViewLayout attribute:NSLayoutAttributeCenterY relatedBy:NSLayoutRelationEqual toItem:topLayout attribute:NSLayoutAttributeCenterY multiplier:1.0 constant:0.0];
NSLayoutConstraint *childViewControlsHtConstraints = [NSLayoutConstraint constraintWithItem:childViewLayout  attribute:NSLayoutAttributeHeight relatedBy:NSLayoutRelationEqual toItem:topLayout attribute:NSLayoutAttributeHeight multiplier:1.0 constant:0.0];

[topLayout addConstraint:childViewControlsHConstraints];
[topLayout addConstraint:childViewControlsVConstraints];
//[topLayout addConstraint:childViewControlsHtConstraints];

// Instruction  field
UILabel* instructionFieldLbl = [[UILabel alloc]init];
[childViewLayout addSubview:instructionFieldLbl];
[instructionFieldLbl setText:@"Please check your SMS or E-Mail for the 4 digit actiation code. Please enter the same to activat your account"];
UIFont *instructionFieldLblFont = [UIFont fontWithName:@"Arial-BoldMT" size:13];
[instructionFieldLbl setFont:instructionFieldLblFont];
instructionFieldLbl.numberOfLines = 0;
[instructionFieldLbl sizeToFit];
[instructionFieldLbl setTextColor:[UIColor grayColor]];
instructionFieldLbl.translatesAutoresizingMaskIntoConstraints = NO;



NSLayoutConstraint  *instructionFieldHConstraint = [NSLayoutConstraint constraintWithItem:instructionFieldLbl attribute:NSLayoutAttributeCenterX relatedBy:NSLayoutRelationLessThanOrEqual toItem:childViewLayout attribute:NSLayoutAttributeCenterX multiplier:1.0 constant:0.0f];
//NSArray *instructionFieldHConstraints = [NSLayoutConstraint constraintsWithVisualFormat:@"H:|-10-[instructionFieldLbl]-10-|" options:0 metrics:nil views:@{@"instructionFieldLbl": instructionFieldLbl}];
[childViewLayout addConstraint:instructionFieldHConstraint];
//[childViewLayout addConstraints:instructionFieldHConstraints];
dispatch_async(dispatch_get_main_queue(), ^{
    instructionFieldLbl.preferredMaxLayoutWidth = self.view.bounds.size.width;
});

// Activation field
self->m_ObjActivationField = [[JVFloatLabeledTextField alloc]init];
[childViewLayout addSubview:self->m_ObjActivationField];
self->m_ObjActivationField.borderStyle = UITextBorderStyleRoundedRect;

self->m_ObjActivationField.translatesAutoresizingMaskIntoConstraints = NO;
self->m_ObjActivationField.placeholder = [NSString stringWithFormat:@"Enter the activtion code"];


NSLayoutConstraint  *activationHorzConstraint = [NSLayoutConstraint constraintWithItem:self->m_ObjActivationField attribute:NSLayoutAttributeCenterX relatedBy:NSLayoutRelationEqual toItem:childViewLayout attribute:NSLayoutAttributeCenterX multiplier:1.0 constant:0.0];
[childViewLayout addConstraint:activationHorzConstraint];


NSDictionary *myControlViews = @{
                             @"instructionFieldLbl": instructionFieldLbl,
                             @"activationField": self->m_ObjActivationField
                             };

NSArray *myControlViewsVConstraints = [NSLayoutConstraint constraintsWithVisualFormat:@"V:|[instructionFieldLbl]-10-[activationField]|" options:0 metrics:nil views:myControlViews];
[childViewLayout addConstraints:myControlViewsVConstraints];


// Submit button
self->m_ObjActivationBut = [[UIButton alloc]init];
[topLayout addSubview:self->m_ObjActivationBut];
[self->m_ObjActivationBut setTitle: [NSString stringWithFormat:@"Activate"] forState:UIControlStateNormal];
self->m_ObjActivationBut.backgroundColor = [UIColor redColor];
[self->m_ObjActivationBut setTitleColor:[UIColor whiteColor] forState:UIControlStateNormal];
self->m_ObjActivationBut.translatesAutoresizingMaskIntoConstraints = NO;
self->m_ObjActivationBut.layer.cornerRadius = 10;
self->m_ObjActivationBut.clipsToBounds = YES;


NSDictionary *topViews = @{
                             @"childViewLayout": childViewLayout,
                             @"activationButton": self->m_ObjActivationBut
                             };

//NSArray *myTopVConstraints = [NSLayoutConstraint constraintsWithVisualFormat:@"V:|[activationButton(40)]-10-|" options:0 metrics:nil views:topViews];
NSArray *myTopHConstraints = [NSLayoutConstraint constraintsWithVisualFormat:@"H:|-[activationButton]-|" options:0 metrics:nil views:@{@"activationButton": self->m_ObjActivationBut}];

NSLayoutConstraint  *myTopVConstraints = [NSLayoutConstraint constraintWithItem:self->m_ObjActivationBut attribute:NSLayoutAttributeBottom relatedBy:NSLayoutRelationEqual toItem:topLayout attribute:NSLayoutAttributeBottom multiplier:1.0 constant:-10.0f];

[topLayout addConstraint:myTopVConstraints];
[topLayout addConstraints:myTopHConstraints];