前言：系统自带的textview是没有添加占位文字的功能的，我们可以通过自定义即可实现此功能
- 自定义textview
#import <UIKit/UIKit.h>
@interface TextView : UITextView
/** 占位文字 */
@property(nonatomic, copy) NSString *placeholder;
/** 占位文字颜色 */
@property(nonatomic, strong) UIColor *placeholderColor;
@end
#import "TextView.h"
@implementation TextView
- (instancetype)initWithFrame:(CGRect)frame
{
if (self = [super initWithFrame:frame]) {
// 设置默认字体
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
{
//移除通知
[[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 光标与文字不一致,设置尺寸
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
- 在外部调用
#import "ViewController.h"
#import "TextView.h"
@interface ViewController (）
@property(nonatomic, strong) TextView *textView;
@end
@implementation ViewController
- (void)viewDidLoad {
[super viewDidLoad];
TextView *textView = [[TextView alloc] init];
textView.frame = self.view.bounds;
//设置可以上下拖动
textView.alwaysBounceVertical = YES;
textView.delegate = self;
textView.placeholder = @"我是占位文字....我是占位文字....我是占位文字....我是占位文字....我是占位文字....我是占位文字....哈哈哈";
[self.view addSubview:textView];
self.textView = textView;
}
- (void)didReceiveMemoryWarning {
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
@end
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