objective-c ios 自动布局 NSLayoutConstraint

Question

UIView* headerView = [[UIView alloc] initWithFrame:CGRectMake(8, 8, frameWidth, frameHeight)];
    headerView.backgroundColor = UIColorFromRGB(0x5F70B9);
    
    UIImage* leftImage = [UIImage imageNamed: @"search_list"];
    UIImageView* leftImageView = [[UIImageView alloc] initWithImage: leftImage];
    [leftImageView setFrame: CGRectMake(10, 15, 70, 50)]; // CGRectMake(10, 15, 70, 50)

    UITextView* textView = [[UITextView alloc] initWithFrame:CGRectMake(80, 20, 160, 40)];
    textView.backgroundColor = UIColorFromRGB(0x5F70B9);
    textView.textColor = UIColorFromRGB(0xFFFFFF);
    [textView setFont:[UIFont preferredFontForTextStyle:UIFontTextStyleTitle3]];
    textView.text = STLocalizedString(@"message_overall_non_reply");
    textView.editable = NO;
    
    UIImage* rightImage = [UIImage imageNamed: @"arrow_mask"];
    UIImageView* rightImageView = [[UIImageView alloc] initWithImage: rightImage];
    [rightImageView setFrame:CGRectMake(380, 30, 15, 20)];
    
    [headerView addSubview: leftImageView];
    [headerView addSubview: textView];
    [headerView addSubview: rightImageView];

期望图像： enter image description here

现在我正在对原点 x、y 和所有内容进行硬编码。我想使用自动布局，以便左图像和右图像充当前导和尾随图标。

有什么建议吗？

试过类似下面的东西，但没有工作： `

[leftImageView setTranslatesAutoresizingMaskIntoConstraints:NO];

NSLayoutConstraint *leftImageViewConstraint = [NSLayoutConstraint constraintWithItem: leftImage attribute: NSLayoutAttributeLeading relatedBy: NSLayoutRelationEqual toItem: headerView attribute: NSLayoutAttributeLeading multiplier: 1 constant: 0];

[leftImageView addConstraints: @[leftImageViewConstraint]];

`

Answer 1

您需要激活您添加的每个约束。当您有一堆约束要设置时，使用 NSLayoutConstraint activateConstraints 会容易得多。并且使用各种“锚点”属性来设置约束比使用创建 NSLayoutConstraint 的长格式更简单。

这是您的代码更新了很多约束：

UIView* headerView = [[UIView alloc] initWithFrame:CGRectMake(8, 8, frameWidth, frameHeight)];
headerView.backgroundColor = UIColorFromRGB(0x5F70B9);

UIImage* leftImage = [UIImage imageNamed: @"search_list"];
UIImageView* leftImageView = [[UIImageView alloc] initWithImage: leftImage];

UITextView* textView = [[UITextView alloc] initWithFrame:CGRectZero];
textView.backgroundColor = UIColorFromRGB(0x5F70B9);
textView.textColor = UIColorFromRGB(0xFFFFFF);
textView.font = [UIFont preferredFontForTextStyle:UIFontTextStyleTitle3];
textView.text = STLocalizedString(@"message_overall_non_reply");
textView.editable = NO;

UIImage* rightImage = [UIImage imageNamed: @"arrow_mask"];
UIImageView* rightImageView = [[UIImageView alloc] initWithImage: rightImage];

leftImageView.translatesAutoresizingMaskIntoConstraints = NO;
textView.translatesAutoresizingMaskIntoConstraints = NO;
rightImageView.translatesAutoresizingMaskIntoConstraints = NO;

[headerView addSubview: leftImageView];
[headerView addSubview: textView];
[headerView addSubview: rightImageView];

[NSLayoutConstraint activateConstraints:@[
    [leftImageView.leadingAnchor constraintEqualToAnchor:headerView.leadingAnchor constant:10],
    //[leftImageView.topAnchor constraintEqualToAnchor:headerView.topAnchor constant:15],
    [leftImageView.centerYAnchor constraintEqualToAnchor:headerView.centerYAnchor],
    [leftImageView.widthAnchor constraintEqualToConstant:70],
    [leftImageView.heightAnchor constraintEqualToConstant:50],
    [rightImageView.trailingAnchor constraintEqualToAnchor:headerView.trailingAnchor constant:-10],
    //[rightImageView.topAnchor constraintEqualToAnchor:headerView.topAnchor constant:30],
    [rightImageView.centerYAnchor constraintEqualToAnchor:headerView.centerYAnchor],
    [rightImageView.widthAnchor constraintEqualToConstant:15],
    [rightImageView.heightAnchor constraintEqualToConstant:20],
    [textView.leadingAnchor constraintEqualToAnchor:leftImageView.trailingAnchor constant:10],
    [textView.trailingAnchor constraintEqualToAnchor:rightImageView.leadingAnchor constant:-10],
    [textView.topAnchor constraintEqualToAnchor:headerView.topAnchor constant:20],
    [textView.bottomAnchor constraintEqualToAnchor:headerView.bottomAnchor constant:-20],
]];

我在这里做了一些猜测。显然，您可以更改这些以满足您的需要。