iOS Demo 详解(一) 占位符的TextView

电脑中有很多demo,打算仔细研究下,顺便分享,挺多忘了原地址就不贴,非常抱歉

这次分享 JYHTextView 略有修改

效果

冯绍峰粉色粉色.gif

.h

Paste_Image.png

.m

#import "JYHTextView.h"

@interface JYHTextView()

//占位 label
@property(nonatomic, weak)UILabel *placeholderLabel;

@end
@implementation JYHTextView

- (instancetype)initWithFrame:(CGRect)frame
{
    self = [super initWithFrame:frame];
    if (self) {
        self.backgroundColor = [UIColor clearColor];
        
        //添加一个显示占位文字的Label
        UILabel *placeholderLabel = [[UILabel alloc]initWithFrame:CGRectMake(3, 5, 200, 20)];

        // 背景颜色透明
        placeholderLabel.backgroundColor = [UIColor clearColor];

        [self addSubview:placeholderLabel];
        
        self.placeholderLabel = placeholderLabel;
        
        //设置占位文字颜色
        self.placeholderColor = [UIColor lightGrayColor];
        //设置默认字体大小
        self.font = [UIFont systemFontOfSize:15];
        
        //设置监听通知
        [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(textChange) name:UITextViewTextDidChangeNotification object:self];
    }
    return self;
}

/**
 *   移除本控制器所有的通知；
 */
- (void)dealloc
{
    [[NSNotificationCenter defaultCenter] removeObserver:self];
}



/**
 *  文字内容改变时调用的方法
 */
- (void)textChange {
    //  非0即为真    输入文字后 隐藏占位label
    self.placeholderLabel.hidden = (self.text.length != 0);
}




/**
 * set 赋值  
 */
- (void)setPlaceholder:(NSString *)placeholder {
    //copy 保证按钮 因为不可修改
    _placeholder = [placeholder copy];
    
    self.placeholderLabel.text = placeholder;
}


- (void)setPlaceholderColor:(UIColor *)placeholderColor {
    _placeholderColor = placeholderColor;
    self.placeholderLabel.textColor = placeholderColor;
}


- (void)setText:(NSString *)text {
    [super setText:text];
    
    [self textChange];
}


@end

使用方法

Paste_Image.png

demo 下载地址:
https://git.oschina.net/wwwzz/JYHTextView