监听TextFiled输入字符改变后的两种方式

1、[self.tfQueryaddTarget:selfaction:@selector(valueChanged:) forControlEvents:UIControlEventEditingChanged];

注意这里是UIControlEventEditingChanged而不是UIControlEventValueChanged

2、[[NSNotificationCenter defaultCenter] addObserver:self

selector:@selector(changeValue:) name:UITextFieldTextDidChangeNotificationobject:self];

3、监听输入前的方法：shouldChangeCharactersInRange