其实需求很简单，想必你也会！但是万一有需要的同学呢！废话少说，看需求效果图：
WechatIMG2983.jpeg
WechatIMG2986.jpeg
WechatIMG2991.jpeg
textView正常情况下是没有占位符的，但是我们可以通过继承与textview 用他的drawRect方法绘制，代码如下：
.h文件中添加属性
@interface DXFeedBackTextView : UITextView
/** 占位文字 /
@property(nonatomic, copy) NSString placeholder;
/ 占位文字颜色 */
@property(nonatomic, strong) UIColor *placeholderColor;
@end
.m文件中实现代码如：
@implementation DXFeedBackTextView
- (instancetype)init{
if (self = [super init]) {
// 设置默认字
self.font = [UIFont systemFontOfSize:17];
// 设置默认颜色
self.placeholderColor = [UIColor grayColor];
// 使用通知监听文字改变
[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(textDidChange:) name:UITextViewTextDidChangeNotification object:self];
}
return self;
}
- (void)textDidChange:(NSNotification *)note{
// 会重新调用drawRect:方法
[self setNeedsDisplay];
}
- (void)dealloc{
[[NSNotificationCenter defaultCenter] removeObserver:self];
}
/**
* 每次调用drawRect:方法，都会将以前画的东西清除掉
*/
- (void)drawRect:(CGRect)rect{
// 如果有文字，就直接返回，不需要画占位文字
if (self.hasText) return;
// 属性
NSMutableDictionary *attrs = [NSMutableDictionary dictionary];
attrs[NSFontAttributeName] = self.font;
attrs[NSForegroundColorAttributeName] = self.placeholderColor;
// 画文字
rect.origin.x = 5;
rect.origin.y = 8;
rect.size.width -= 2 * rect.origin.x;
[self.placeholder drawInRect:rect withAttributes:attrs];
}
- (void)layoutSubviews{
[super layoutSubviews];
[self setNeedsDisplay];
}
#pragma mark - setter
//重写setter方法调用setNeedsDisplay方法刷新
- (void)setPlaceholder:(NSString *)placeholder{
_placeholder = [placeholder copy];
[self setNeedsDisplay];
}
- (void)setPlaceholderColor:(UIColor *)placeholderColor{
_placeholderColor = placeholderColor;
[self setNeedsDisplay];
}
- (void)setFont:(UIFont *)font{
[super setFont:font];
[self setNeedsDisplay];
}
- (void)setText:(NSString *)text{
[super setText:text];
[self setNeedsDisplay];
}
- (void)setAttributedText:(NSAttributedString *)attributedText{
[super setAttributedText:attributedText];
[self setNeedsDisplay];
}
@end
打完收工！
