iphone自定义UITextView的placeholder

大家都知道UITextField才有placeholder属性，UITextView 并没有placeholder，那么怎么模拟UITextfield使UITextView也有placeholder。

思路是：继承uitextview，判断当text为空时就让[super text]显示placeholder。

代码如下（我引用了arc）：

UIPlaceholderTextView.h

#import <UIKit/UIKit.h>@interface UIPlaceholderTextView : UITextView@property(nonatomic, strong) NSString *placeholder;     //占位符-(void)addObserver;//添加通知-(void)removeobserver;//移除通知@end

UIPlaceholderTextView.m

#import "UIPlaceholderTextView.h"@interface UIPlaceholderTextView ()@property (nonatomic, strong) UIColor* textColor;- (void) beginEditing:(NSNotification*) notification;- (void) endEditing:(NSNotification*) notification;@end@implementation UIPlaceholderTextView@synthesize placeholder;@synthesize textColor;- (id) initWithFrame:(CGRect)frame {    if ((self = [super initWithFrame:frame])) {        [self awakeFromNib];    }    return self;}//当用nib创建时会调用此方法- (void)awakeFromNib {    textColor = [UIColor redColor];    [self addObserver];}-(void)addObserver{    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(beginEditing:) name:UITextViewTextDidBeginEditingNotification object:self];    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(endEditing:) name:UITextViewTextDidEndEditingNotification object:self];}-(void)removeobserver{    [[NSNotificationCenter defaultCenter] removeObserver:self];}#pragma mark -#pragma mark Setter/Getters- (void) setPlaceholder:(NSString *)aPlaceholder {    placeholder = aPlaceholder;    [self endEditing:nil];}- (NSString *) text {    NSString* text = [super text];    if ([text isEqualToString:placeholder]) return @"";    return text;}- (void) beginEditing:(NSNotification*) notification {    if ([super.text isEqualToString:placeholder]) {        super.text = nil;        //字体颜色        [super setTextColor:textColor];    }    }- (void) endEditing:(NSNotification*) notification {    if ([super.text isEqualToString:@""] || self.text == nil) {        super.text = placeholder;        //注释颜色        [super setTextColor:[UIColor lightGrayColor]];    }}

在ViewController中用时，1、在xib上加一个uitextview连接上，2、直接创建initframe

但是不要忘了，placeholder，和添加通知，移除通知。

- (void)viewDidLoad{    [super viewDidLoad];    self.textView.placeholder = @"请添写你的信息……";    // Do any additional setup after loading the view, typically from a nib.}-(void)viewDidAppear:(BOOL)animated{    [super viewDidAppear:YES];    [self.textView addObserver];}-(void)viewDidDisappear:(BOOL)animated{    [super viewDidDisappear:YES];    [self.textView removeobserver];}

效果图：

     

欢迎大家，有更好的方法提出！