1.判断内容是否为空

- (BOOL)textView:(UITextView *)textView shouldChangeTextInRange:(NSRange)range replacementText:(NSString *)text

{

NSMutableString * changedString=[[NSMutableString alloc]initWithString:textView.text];

[changedString replaceCharactersInRange:range withString:text];

if (changedString.length!=0) {

_warnLabel.text = @"";

}

return YES;

}

- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string

{

NSMutableString * changedString=[[NSMutableString alloc]initWithString:textField.text];

[changedString replaceCharactersInRange:range withString:string];

if (changedString.length!=0) {

//        self.navigationItem.rightBarButtonItem.enabled=YES;

}else{

//        self.navigationItem.rightBarButtonItem.enabled=NO;

}

return YES;

}