VFL的应用

- (void)setLayout
{
    for (UIView *view in [self.contentView subviews]) {
        view.translatesAutoresizingMaskIntoConstraints = NO;
    }
    
    NSDictionary *viewsDict = NSDictionaryOfVariableBindings(_titleLabel, _bodyLabel, _authorLabel, _timeLabel, _commentCount);
    //titlelable 与视图的间距为8，与bobyLabel的间距为5，纵向，左右对齐
    [self.contentView addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"V:|-8-[_titleLabel]-5-[_bodyLabel]" options:NSLayoutFormatAlignAllLeft | NSLayoutFormatAlignAllRight metrics:nil views:viewsDict]];
    
    //bodyLabel的与authroLabel的间距为5，_authorLabel间距与视图的间距为8，左对齐
    [self.contentView addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"V:[_bodyLabel]-5-[_authorLabel]-8-|"
                                                                             options:NSLayoutFormatAlignAllLeft
                                                                             metrics:nil
                                                                               views:viewsDict]];
    //横向间距，titleLabel与左右视图的间距为8
    [self.contentView addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"|-8-[_titleLabel]-8-|"
                                                                             options:0
                                                                             metrics:nil
                                                                               views:viewsDict]];
    //横向间距 _authorLabel与timeLabel的间距为10， timeLabel 与视图间距为8，上下对齐
    [self.contentView addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"[_authorLabel]-10-[_timeLabel]-10-[_commentCount]"
                                                                             options:NSLayoutFormatAlignAllTop | NSLayoutFormatAlignAllBottom
                                                                             metrics:nil
                                                                               views:viewsDict]];
}

 

 

 

UILabel *nameLabel = [UILabel new];
    nameLabel.text = usersInformation[0];
    nameLabel.font = [UIFont boldSystemFontOfSize:20];
    nameLabel.textColor = [UIColor colorWithHex:0x696969];
    nameLabel.translatesAutoresizingMaskIntoConstraints = NO;
    [headerView addSubview:nameLabel];
    
    NSDictionary *views = NSDictionaryOfVariableBindings(portraitView, nameLabel);
    //metrics传入参数，x = 多少，
    NSDictionary *metrics = @{@"x": @([UIScreen mainScreen].bounds.size.width / 4 - 15)};
    
    //NSLayoutFormatAlignAllCenterX 居中对齐
    [headerView addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"V:[portraitView(60)]-10-[nameLabel]-15-|" options:NSLayoutFormatAlignAllCenterX metrics:nil views:views]];
    
    //表示x = metrics定义的值,portraitView距离x的距离
    [headerView addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"|-x-[portraitView(60)]" options:0 metrics:metrics views:views]];
    
    portraitView.userInteractionEnabled = YES;
    nameLabel.userInteractionEnabled = YES;
    [portraitView addGestureRecognizer:[[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(pushLoginPage)]];
    [nameLabel addGestureRecognizer:[[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(pushLoginPage)]];

 

- (void)setLayout
{
    UIImageView *email = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"login-email"]];
    email.contentMode = UIViewContentModeScaleAspectFill;
    
    UIImageView *password = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"login-password"]];
    password.contentMode = UIViewContentModeScaleAspectFit;
    
    [self.view addSubview:email];
    [self.view addSubview:password];
    
    for (UIView *view in [self.view subviews]) { view.translatesAutoresizingMaskIntoConstraints = NO;}
    
    NSDictionary *views = NSDictionaryOfVariableBindings(email, password, _accountField, _passwordField, _loginButton, _registerInfo);
    
    [self.view addConstraint:[NSLayoutConstraint constraintWithItem:self.view  attribute:NSLayoutAttributeCenterX relatedBy:NSLayoutRelationEqual
                                                             toItem:_loginButton attribute:NSLayoutAttributeCenterX multiplier:1 constant:0]];
    
    [self.view addConstraint:[NSLayoutConstraint constraintWithItem:self.view attribute:NSLayoutAttributeCenterY relatedBy:NSLayoutRelationEqual
                                                             toItem:_loginButton attribute:NSLayoutAttributeCenterY multiplier:1 constant:0]];
    
    [self.view addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"V:[email(20)]-20-[password(20)]-30-[_loginButton(40)]"
                                                                      options:0 metrics:nil views:views]];
    [self.view addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"|-20-[_loginButton]-20-|" options:0 metrics:nil views:views]];
    [self.view addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"V:[_loginButton]-20-[_registerInfo(30)]"
                                                                      options:NSLayoutFormatAlignAllLeft | NSLayoutFormatAlignAllRight
                                                                      metrics:nil views:views]];
    //垂直居中显示,X轴方向对齐
    [self.view addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"|-30-[email(20)]-[_accountField]-30-|"     options:NSLayoutFormatAlignAllCenterY metrics:nil views:views]];
    [self.view addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"|-30-[password(20)]-[_passwordField]-30-|" options:NSLayoutFormatAlignAllCenterY metrics:nil views:views]];
}

 

 

  //如果是横向方向设置的中心点对齐，调用NSLayoutFormatAlignAllCenterX会崩溃，同理，如果是纵向方向，如果调用是NSLayoutFormatAlignAllCenterY,也会崩溃的

    [self.view addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"H:|-100-[redview(100)]-20-[blueView]-30-|"                                              options:NSLayoutFormatAlignAllCenterX metrics:nil views:views]];

 

options:NSLayoutFormatAlignAllCenterX 水平居中

options:NSLayoutFormatAlignAllCenterY 垂直居中