//PlaceholderTextView.m
//Copyright (c) All rights reserved.
#import"PlaceholderTextView.h"
@interface PlaceholderTextView()
/**占位文字label */
/**占位文字*/
@property(nonatomic,copy)NSString*placeholder;
/**占位文字的颜色*/
@property(nonatomic,strong)UIColor*placeholderColor;
@property(nonatomic,weak)UILabel*placeholderLabel;
@end
@implementation PlaceholderTextView
- (UILabel*)placeholderLabel
{
if(!_placeholderLabel) {
//添加一个用来显示占位文字的label
UILabel*placeholderLabel = [[UILabel alloc] init];
placeholderLabel.numberOfLines=0;
placeholderLabel.x=4;
placeholderLabel.y=7;
[self addSubview:placeholderLabel];
_placeholderLabel= placeholderLabel;
}
return_placeholderLabel;
}
- (instancetype)initWithFrame:(CGRect)frame
{
if(self= [super initWithFrame:frame]) {
//垂直方向上永远有弹簧效果
self.alwaysBounceVertical=YES;
//默认字体
self.font= [UIFont systemFontOfSize:15];
//默认的占位文字颜色
self.placeholderColor= [UIColor grayColor];
//监听文字改变
[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(textDidChange) name:UITextViewTextDidChangeNotification object:nil];
}
returnself;
}
- (void)dealloc
{
[XMGNoteCenterremoveObserver:self];
}
/**
*监听文字改变
*/
- (void)textDidChange
{
//只要有文字,就隐藏占位文字label
self.placeholderLabel.hidden=self.hasText;
}
/**
*更新占位文字的尺寸
*/
- (void)layoutSubviews
{
[super layoutSubviews];
self.placeholderLabel.width=self.width-2*self.placeholderLabel.x;
[self.placeholderLabel sizeToFit];
}
#pragma mark -重写setter
- (void)setPlaceholderColor:(UIColor*)placeholderColor
{
_placeholderColor= placeholderColor;
self.placeholderLabel.textColor= placeholderColor;
}
- (void)setPlaceholder:(NSString*)placeholder
{
_placeholder= [placeholder copy];
self.placeholderLabel.text= placeholder;
[self setNeedsLayout];
}
- (void)setFont:(UIFont*)font
{
[super setFont:font];
self.placeholderLabel.font= font;
[self setNeedsLayout];
}
- (void)setText:(NSString*)text
{
[super setText:text];
[self textDidChange];
}
- (void)setAttributedText:(NSAttributedString*)attributedText
{
[super setAttributedText:attributedText];
[self textDidChange];
}
/**
* setNeedsDisplay方法:会在恰当的时刻自动调用drawRect:方法
* setNeedsLayout方法:会在恰当的时刻调用layoutSubviews方法
*/
@end
