iOS - 创建可以在 InterfaceBuilder 中实时预览的自定义控件

一、需求实现一个前后带图标的输入框

这是一个简单的自定义控件,很容易想到自定义一个视图(UIView),然后前后的图标使用 UIImageView 或者 UIButton 显示,中间放一个 UITextField 就可以了

实现方式上可以 InterfaceBuilder 创建,也可以使用纯代码实现,这个可以根据自己喜好及项目确定

iOS - 创建可以在 InterfaceBuilder 中实时预览的自定义控件

二、实现 InterfaceBuilder 中实时预览

要实现上面的一个需求,相信对大多数人来说并不难,本文主要讲解怎么让自定义控件支持纯代码创建,并且也支持在 InterfaceBuilder 中实时预览,以及本人在编写过程中遇到问题

想要让自定义的控件支持在 InterfaceBuilder 中实时预览,其实也并不难,需要用到两个关键字 IB_DESIGNABLE 和 IBInspectable

IB_DESIGNABLE:用来指示该类可以在 InterfaceBuilder ,在 InterfaceBuilder 中,添加一个 UIView 后,指定 Custom Class 中的 Class 为该类就可以了;这个关键字可以下载 .h 或者 .m 中 @interface 前面即可

代码如下:

IB_DESIGNABLE
@interface ImageTextField : UIView

IBInspectable:用来指示属性在 InterfaceBuilder 中显示属性,可以实时设置;这个关键字只用添加到属性类型前面即可

代码如下:

@property (nonatomic, strong) IBInspectable NSString *text;

这样准备工作,接下来就是在具体实现过程

三、实现及注意事项

1. 纯代码初始化

  对于纯代码创建,我们要有一个初始化方法,init 或者 initWithFrame 或者自定义的初始化方法,我们只需要把创建添加子控件在初始化方法中一步一步添加即可,代码约束可以添加到 layoutSubviews

#pragma mark --- 支持代码创建
- (instancetype)initWithFrame:(CGRect)frame {
    if (self = [super initWithFrame:frame]) {
        [self setViewsWithFrame:frame];
    }

    return self;
}
- (void)layoutSubviews {
    [super layoutSubviews];
    
    // 约束在这里添加,才能保证约束正确执行
    [self setConstraints];
}

必须要重写初始化方法:- (instancetype)initWithFrame:(CGRect)frame 我们在使用 InterfaceBuilder 的时候,会调用该方法,所以修改该方法调用的代码都会实时显示到 InterfaceBuilder 中,如果是我们自定义的初始化方法,则不会在修改代码时实时显示,我们为了能够实时预览到修改效果,需要重写系统的初始化方法,同时为了支持纯代码创建实例,

可以把初始化要实现的代码封装起来,这样的话可以方便的在自定义以及重写的初始化方法中方便调用。

那么怎么才能让我们的修改实时显示在,我们需要实现另外一个方法:prepareForInterfaceBuilder 从方法名称就可以猜测到,写在该方法中的代码会反映的到 InterfaceBuilder 这样就能看到实时修改后的效果

示例代码:

#pragma mark --- 实时更新到 InterfaceBuilder
- (void)prepareForInterfaceBuilder {
   [self setConstraints]; }

为什么在这里调用?如果在 init 中调用,会导致在 InterfaceBuilder 设置的属性不起作用,那么就看不到真实的效果。这里的代码只是在设计的时候会调用,真实的设置约束的代码是在 layoutSubviews 中调用

2. 不使用纯代码创建

我们只需要在 InterfaceBuilder 中添加一个 UIView 中,然后设置 Class 为自定义的控件就可以了,但是可视化添加的控件,怎么初始化呢?就需要重写下面这个方法来保证正确的运行,在程序运行时,系统会自动调用这个方法创建实例

#pragma mark --- 支持XIB创建
- (instancetype)initWithCoder:(NSCoder *)aDecoder {
    if (self = [super initWithCoder:aDecoder]) {
        // 这里 Frame 可以任意指定,约束会调整视图大小
         [self setViewsWithFrame:CGRectZero];
    }
    
    return self;
}

 

完整代码如下

 ImageTextField.h:

//
//  ImageTextField.h
//  EXOTerra
//
//  带有图片提示的输入框
//
//  Created by huang zhengguo on 2020/1/2.
//  Copyright © 2020 Inledco. All rights reserved.
//

#import <UIKit/UIKit.h>

NS_ASSUME_NONNULL_BEGIN

IB_DESIGNABLE
@interface ImageTextField : UIView

// 文字
@property (nonatomic, strong) IBInspectable NSString *text;
// 前面图像
@property (nonatomic, strong) IBInspectable UIImage *image;
// 字体颜色
@property (nonatomic, strong) IBInspectable UIColor *textColor;
// 占位符
@property (nonatomic, strong) IBInspectable NSString *placeholder;
// 占位符颜色
@property (nonatomic, strong) IBInspectable UIColor *placeholderColor;
// 是否隐藏输入
@property (nonatomic, assign) IBInspectable BOOL secureTextEntry;
// 小图标
@property (nonatomic, strong) IBInspectable UIImage *iconImage;
// 是否显示小图标
@property (nonatomic, assign) IBInspectable BOOL isIconVisible;
// 小图标点击回调
@property (nonatomic, copy) void (^iconButtonClickCallback) (ImageTextField *, UIButton *, BOOL);

@end

NS_ASSUME_NONNULL_END
ImageTextField.m
//
//  ImageTextField.m
//  EXOTerra
//
//  Created by huang zhengguo on 2020/1/2.
//  Copyright © 2020 Inledco. All rights reserved.
//

#import "ImageTextField.h"

@interface ImageTextField()

// 前面图标
@property (nonatomic, strong) UIImageView *headerImageView;
// 输入框
@property (nonatomic, strong) UITextField *textField;
// 后面图标
@property (nonatomic, strong) UIButton *iconButton;

@end

@implementation ImageTextField

#pragma mark --- 支持代码创建
- (instancetype)initWithFrame:(CGRect)frame {
    if (self = [super initWithFrame:frame]) {
        [self setViewsWithFrame:frame];
    }

    return self;
}

#pragma mark --- 支持XIB创建
- (instancetype)initWithCoder:(NSCoder *)aDecoder {
    if (self = [super initWithCoder:aDecoder]) {
        // 这里 Frame 可以任意指定,在 InterfaceBuilder 中会重新设定
        [self setViewsWithFrame:CGRectZero];
    }
    
    return self;
}#pragma mark --- 添加子视图等
- (void)setViewsWithFrame:(CGRect)frame {
    self.layer.borderWidth = 1.0;
    self.layer.borderColor = [UIColor whiteColor].CGColor;
    self.layer.cornerRadius = 3.0;
    
    // 前端图片
    self.headerImageView = [[UIImageView alloc] initWithFrame:CGRectZero];
    self.headerImageView.translatesAutoresizingMaskIntoConstraints = NO;
    
    [self addSubview:self.headerImageView];
    
    // 输入框
    self.textField = [[UITextField alloc] init];
    self.textField.translatesAutoresizingMaskIntoConstraints = NO;

    [self addSubview:self.textField];
    
    // 尾部小按钮图标
    self.iconButton = [[UIButton alloc] initWithFrame:CGRectZero];
    self.iconButton.translatesAutoresizingMaskIntoConstraints = NO;
    [self.iconButton addTarget:self action:@selector(iconButtonClickAction:) forControlEvents:UIControlEventTouchUpInside];
    
    [self addSubview:self.iconButton];
    
    // 默认设置
    self.placeholderColor = [UIColor lightGrayColor];
}

#pragma mark --- 小图标点击方法
- (void)iconButtonClickAction:(UIButton *)sender {
    if (self.iconButtonClickCallback) {
        self.iconButtonClickCallback(self, sender, self.secureTextEntry);
    }
}

- (void)setImage:(UIImage *)image {
    _image = image;
    _headerImageView.image = _image;
}

- (NSString *)text {
    return _textField.text;
}

- (void)setText:(NSString *)text {
    _textField.text = text;
}

- (void)setTextColor:(UIColor *)textColor {
    _textColor = textColor;
    _textField.textColor = _textColor;
}

- (void)setPlaceholder:(NSString *)placeholder {
    _placeholder = placeholder;
    _textField.placeholder = _placeholder;
}

- (void)setPlaceholderColor:(UIColor *)placeholderColor {
    if (_placeholder == nil || _placeholder.length == 0) {
        return;
    }
    _placeholderColor = placeholderColor;
    NSMutableAttributedString *placeholderAttributedString = [[NSMutableAttributedString alloc] initWithString:_placeholder];
    
    [placeholderAttributedString addAttribute:NSForegroundColorAttributeName value:_placeholderColor range:NSMakeRange(0, _placeholder.length)];
    
    _textField.attributedPlaceholder = placeholderAttributedString;
}

- (void)setSecureTextEntry:(BOOL)secureTextEntry {
    _secureTextEntry = secureTextEntry;
    _textField.secureTextEntry = _secureTextEntry;
}

- (void)setIconImage:(UIImage *)iconImage {
    _iconImage = iconImage;
    if (_iconImage) {
        [_iconButton setImage:_iconImage forState:UIControlStateNormal];
    }
}

- (void)setIsIconVisible:(BOOL)isIconVisible {
    _isIconVisible = isIconVisible;
    _iconButton.hidden = !_isIconVisible;
}

#pragma mark --- 实时更新到 InterfaceBuilder
- (void)prepareForInterfaceBuilder {
    [self setConstraints];
}

#pragma mark --- 设置约束
- (void)setConstraints {
    // 图片约束
    NSLayoutConstraint *headerImageLeading = [NSLayoutConstraint constraintWithItem:self.headerImageView attribute:NSLayoutAttributeLeading relatedBy:NSLayoutRelationEqual toItem:self attribute:NSLayoutAttributeLeading multiplier:1.0 constant:8.0];
    NSLayoutConstraint *headerImageTop = [NSLayoutConstraint constraintWithItem:self.headerImageView attribute:NSLayoutAttributeTop relatedBy:NSLayoutRelationEqual toItem:self attribute:NSLayoutAttributeTop multiplier:1.0 constant:8.0];
    NSLayoutConstraint *headerImageBottom = [NSLayoutConstraint constraintWithItem:self.headerImageView attribute:NSLayoutAttributeBottom relatedBy:NSLayoutRelationEqual toItem:self attribute:NSLayoutAttributeBottom multiplier:1.0 constant:-8.0];
    NSLayoutConstraint *headerImageWidth = [NSLayoutConstraint constraintWithItem:self.headerImageView attribute:NSLayoutAttributeWidth relatedBy:NSLayoutRelationEqual toItem:self attribute:NSLayoutAttributeHeight multiplier:1.0 constant:-8.0];
    
    [self addConstraints:@[headerImageLeading, headerImageTop, headerImageBottom, headerImageWidth]];
    
    // 小图标约束
    NSLayoutConstraint *iconButtonTop = [NSLayoutConstraint constraintWithItem:self.iconButton attribute:NSLayoutAttributeTop relatedBy:NSLayoutRelationEqual toItem:self attribute:NSLayoutAttributeTop multiplier:1.0 constant:8.0];
    NSLayoutConstraint *iconButtonBottom = [NSLayoutConstraint constraintWithItem:self.iconButton attribute:NSLayoutAttributeBottom relatedBy:NSLayoutRelationEqual toItem:self attribute:NSLayoutAttributeBottom multiplier:1.0 constant:-8.0];
    NSLayoutConstraint *iconButtonTrailing = [NSLayoutConstraint constraintWithItem:self.iconButton attribute:NSLayoutAttributeTrailing relatedBy:NSLayoutRelationEqual toItem:self attribute:NSLayoutAttributeTrailing multiplier:1.0 constant:-8.0];
    NSLayoutConstraint *iconButtonWidth = [NSLayoutConstraint constraintWithItem:self.iconButton attribute:NSLayoutAttributeWidth relatedBy:NSLayoutRelationEqual toItem:self attribute:NSLayoutAttributeHeight multiplier:1.0 constant:-16.0];
    
    if (self.isIconVisible == NO) {
        // 如果图标不可见,设置宽度为0的约束
        iconButtonWidth = [NSLayoutConstraint constraintWithItem:self.iconButton attribute:NSLayoutAttributeWidth relatedBy:NSLayoutRelationEqual toItem:nil attribute:NSLayoutAttributeNotAnAttribute multiplier:1.0 constant:0.0];
    }
    
    [self addConstraints:@[iconButtonWidth, iconButtonTop, iconButtonBottom, iconButtonTrailing]];
    
    // 输入框约束
    NSLayoutConstraint *textFieldImageLeading = [NSLayoutConstraint constraintWithItem:self.textField attribute:NSLayoutAttributeLeading relatedBy:NSLayoutRelationEqual toItem:self.headerImageView attribute:NSLayoutAttributeTrailing multiplier:1.0 constant:8.0];
    NSLayoutConstraint *textFieldImageTop = [NSLayoutConstraint constraintWithItem:self.textField attribute:NSLayoutAttributeTop relatedBy:NSLayoutRelationEqual toItem:self attribute:NSLayoutAttributeTop multiplier:1.0 constant:0.0];
    NSLayoutConstraint *textFieldImageBottom = [NSLayoutConstraint constraintWithItem:self.textField attribute:NSLayoutAttributeBottom relatedBy:NSLayoutRelationEqual toItem:self attribute:NSLayoutAttributeBottom multiplier:1.0 constant:0.0];
    NSLayoutConstraint *textFieldTrailing = [NSLayoutConstraint constraintWithItem:self.textField attribute:NSLayoutAttributeTrailing relatedBy:NSLayoutRelationEqual toItem:self.iconButton attribute:NSLayoutAttributeLeading multiplier:1.0 constant:0.0];
    
    [self addConstraints:@[textFieldImageLeading, textFieldImageTop, textFieldImageBottom, textFieldTrailing]];
}

- (void)layoutSubviews {
    [super layoutSubviews];
    
    // 约束在这里添加,才能保证使用使用代码创建时正常显示
    [self setConstraints];
}

/*
// Only override drawRect: if you perform custom drawing.
// An empty implementation adversely affects performance during animation.
- (void)drawRect:(CGRect)rect {
    // Drawing code
}
*/

@end

iOS - 创建可以在 InterfaceBuilder 中实时预览的自定义控件

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