i have some textfields in my view file,such as:

items: [
xtype: 'textfield',
name: 'name',
itemId: 'txtName',
labelCls: 'input_label',
clearIcon: true
//other code

when i listen the txtName focus event in my controller file,it didn't work;

init: function() {
focus: this.onTxtNameFocus

onTxtNameFocus: function(txt, e, eOpts) {
alert('0'); //it didn't work

can someone tell me where i was wrong? ths.