How to add left padding to the UITextField, when add background Image

#import "QuartzCore/QuartzCore.h"    // First import this Framework

......

UITextField *_emailText = [[UITextField alloc]initWithFrame:CGRectMake(40, 8, 250, 34)];

//    _emailText.borderStyle = UITe;  // Please set borderStyle to default value, otherwise it is not working.

    _emailText.delegate = self;

    _emailText.placeholder = @"Email";

    [_emailText setFont:[UIFont boldSystemFontOfSize:12]];

    _emailText.tag = 1;

    _emailText.returnKeyType = UIReturnKeyNext;

    _emailText.textAlignment = UITextAlignmentLeft;

    _emailText.keyboardType = UIKeyboardTypeEmailAddress;

    _emailText.contentVerticalAlignment = UIControlContentVerticalAlignmentCenter;

    _emailText.leftView = [[UIView alloc] initWithFrame:CGRectMake(0, 0, 12, 20)];

    _emailText.leftViewMode = UITextFieldViewModeAlways;

    _emailText.background = [[UIImage imageNamed:@"textBox.png"] stretchableImageWithLeftCapWidth:7 topCapHeight:17];

    [self.view addSubview:_emailText];