iOS带placeholder的自定义UITextView

前段时间在项目中用到了UITextView,有个需求是要有placeholder,所以就自定义了一个希望能帮到大家.下面请看源码咯
.h文件

#import 

@interface JYTextView : UITextView

@property (nonatomic,copy)NSString *placeholder;
@property (nonatomic,strong) UIColor * placeholderColor;

@end

.m文件

#import "JYTextView.h"

@implementation JYTextView

- (void)awakeFromNib{
    [self ezCustom];
}
- (instancetype)initWithCoder:(NSCoder *)aDecoder{
    if (self = [super initWithCoder:aDecoder]) {
        [self ezCustom];
    }
    return self;
}
- (instancetype)initWithFrame:(CGRect)frame textContainer:(NSTextContainer *)textContainer{
    if (self = [super initWithFrame:frame textContainer:textContainer]) {
        [self ezCustom];
    }
    return self;
}
- (instancetype)init{
    if (self = [super init]) {
        [self ezCustom];
    }
    return self;
}
-(instancetype)initWithFrame:(CGRect)frame
{
    if (self = [super initWithFrame:frame]) {
        [self ezCustom];
    }
    return self;
}
- (void)ezCustom{
    self.layer.cornerRadius = 8;
    [[NSNotificationCenter defaultCenter]addObserver:self selector:@selector(textDidChange) name:UITextViewTextDidChangeNotification object:self];
}
-(void)dealloc{
    [[NSNotificationCenter defaultCenter] removeObserver:self];
}

-(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)textDidChange
{
    [self setNeedsDisplay];
}

-(void)drawRect:(CGRect)rect
{
    if ([self hasText]) return;
    NSMutableDictionary * attrs = [NSMutableDictionary dictionary];
    attrs[NSForegroundColorAttributeName] = self.placeholderColor ? self.placeholderColor : [UIColor grayColor];
    attrs[NSFontAttributeName] = self.font ? self.font : [UIFont systemFontOfSize:12];
    
    CGFloat x = 5;
    CGFloat y = 5;
    CGFloat w = self.frame.size.width - 2 * x;
    CGFloat h = self.frame.size.height - 2 * y;
    CGRect placeholderRect = CGRectMake(x, y, w, h);
    [self.placeholder drawInRect:placeholderRect withAttributes:attrs];
}

-(BOOL)canPerformAction:(SEL)action withSender:(id)sender {
    UIMenuController *menuController = [UIMenuController sharedMenuController];
    if (menuController) {
        [UIMenuController sharedMenuController].menuVisible = NO;
    }
    return NO;
}




@end