ios - UIButton 在其他元素上使用 AutoLayout 时自动调整大小

Question

因此，我在 UIViewController 的不同元素上使用了 NSLayoutConstraints，但由于某些原因它们影响了我的按钮。像这样:

这是我的代码:

// Twitter button
WelcomeButton *twitterButton = [[WelcomeButton alloc] initTwitterButtonWithFrame:CGRectMake(0, 0, 300, 60)];
twitterButton.center = CGPointMake(self.view.frame.size.width / 2, 350);
twitterButton.alpha = 1.0;
twitterButton.translatesAutoresizingMaskIntoConstraints = NO;
[twitterButton addTarget:self action:@selector(twitterSignUpButton:) forControlEvents:UIControlEventTouchUpInside];
[self.view addSubview:twitterButton];

// Facebook button
WelcomeButton *facebookButton = [[WelcomeButton alloc] initFacebookButtonWithFrame:CGRectMake(0, 0, 300, 60)];
facebookButton.center = CGPointMake(self.view.frame.size.width / 2, 0);
facebookButton.alpha = 1.0;
facebookButton.translatesAutoresizingMaskIntoConstraints = NO;
[facebookButton addTarget:self action:@selector(facebookSignUpButton:) forControlEvents:UIControlEventTouchUpInside];
[self.view addSubview:facebookButton];

// Email Sign-Up button
WelcomeButton *emailButton = [[WelcomeButton alloc] initEmailButtonWithFrame:CGRectMake(0, 0, 300, 60)];
emailButton.center = CGPointMake(self.view.frame.size.width / 2, 0);
emailButton.alpha = 1.0;
emailButton.translatesAutoresizingMaskIntoConstraints = NO;
[emailButton addTarget:self action:@selector(emailSignUpButton:) forControlEvents:UIControlEventTouchUpInside];
[self.view addSubview:emailButton];

// Signed-Up Message Label
UILabel *signedUpLabel = [[UILabel alloc] init];
signedUpLabel.frame = CGRectMake(0, 0, 150, 25);
signedUpLabel.center = CGPointMake(self.view.center.x - (signedUpLabel.frame.size.width / 3) + 10, 0);
signedUpLabel.textColor = [UIColor whiteColor];
signedUpLabel.font = [UIFont fontWithName:@"HelveticaNeue-Thin" size:16];
signedUpLabel.text = @"Already Signed Up ?";
signedUpLabel.translatesAutoresizingMaskIntoConstraints = NO;
[self.view addSubview:signedUpLabel];

// Sign-In button
UIButton *signInButton = [UIButton buttonWithType:UIButtonTypeSystem];
signInButton.frame = CGRectMake(0, 0, 100, 25);
signInButton.center = CGPointMake(self.view.center.x + (signedUpLabel.frame.size.width / 3) + 10, 0);
signInButton.titleLabel.textColor = [UIColor whiteColor];
signInButton.titleLabel.font = [UIFont systemFontOfSize:16];
[signInButton setTitle:@"Sign In" forState:UIControlStateNormal];
signInButton.translatesAutoresizingMaskIntoConstraints = NO;
signInButton.autoresizingMask = UIViewAutoresizingFlexibleTopMargin;
[self.view addSubview:signInButton];

这是我的 AutoLayout 代码:

[self.view addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"V:[signedUpLabel]-10-|"
                                                                                          options:0
                                                                                          metrics:0
                                                                                         views:NSDictionaryOfVariableBindings(signedUpLabel)]];
    [self.view addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"V:[signInButton]-2-|"
                                                                      options:0
                                                                      metrics:0
                                                                        views:NSDictionaryOfVariableBindings(signInButton)]];
    [self.view addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"V:[emailButton]-200-[signedUpLabel]"
                                                                      options:0
                                                                      metrics:0
                                                                        views:NSDictionaryOfVariableBindings(emailButton, signedUpLabel)]];
    [self.view addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"V:[facebookButton]-100-[emailButton]"
                                                                      options:0
                                                                      metrics:0
                                                                        views:NSDictionaryOfVariableBindings(facebookButton, emailButton)]];

这里出了什么问题？

我希望它们在一个结构中对齐在一起，但为什么它们会这样显示？当我没有指定任何约束时，它们会正常显示...

Answer 1

你必须添加Horizo​​ntal Constraint

如果您想以编程方式进行，也许您可​​以使用:https://github.com/jrturton/UIView-Autolayout

编辑: 您可以添加一个 Height Constraint，例如:

[self.view addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"V:[myView(==60)]" options:0 metrics:nil views:NSDictionaryOfVariableBindings(myButton)]];