UITextView默认文字提示

在UITextField中自带placeholder属性，可以用于提示输入框信息。但是UITextView并不具备此功能
介绍两种方法来实现：
第一种：
初始化UITextView
//首先定义UITextView  
UITextView *textView = [[UITextView alloc] init];  
textView.font = [UIFont systemFontOfSize:14];  
textView.frame =CGRectMake(10, 0, cell.contentView.bounds.size.width-20, side);  
textView.autoresizingMask = UIViewAutoresizingFlexibleHeight | UIViewAutoresizingFlexibleWidth;  
textView.backgroundColor = [UIColor whiteColor];  
[cell.contentView addSubview:textView];  
textView.hidden = NO;  
textView.delegate = self;  
//其次在UITextView上面覆盖个UILable,UILable设置为全局变量。  
uilabel.frame =CGRectMake(17, 8, cell.contentView.bounds.size.width - side+10, 20);  
uilabel.text = @"请填写审批意见...";  
uilabel.enabled = NO;//lable必须设置为不可用  
uilabel.backgroundColor = [UIColor clearColor];  
[cell.contentView addSubview:uilabel];  
实现UITextView的代理
-(void)textViewDidChange:(UITextView *)textView  
{  
    self.examineText =  textView.text;  
    if (textView.text.length == 0) {  
        uilabel.text = @"请填写审批意见...";  
    }else{  
        uilabel.text = @"";  
    }  
}