Ios UITextField与leftview对齐

我有一个UItextField，在左视图上有一个图像，但我需要UItextField与中心对齐，在左视图中，它向右移动。 代码如下：

self.usernameField = [[UITextField alloc]initWithFrame:CGRectMake(0, 150, self.view.frame.size.width, 50)];
self.usernameField.placeholder = @"E-mail";
[self.usernameField setFont:[UIFont ralewayRegularFontWithSize:20]];
[self.usernameField setValue:[UIColor whiteColor] forKeyPath:@"_placeholderLabel.textColor"];
[self.usernameField setKeyboardType:UIKeyboardTypeEmailAddress];
[self.usernameField setBackground:[UIImage imageNamed:@"background_placeholder"]];
[self.usernameField setTextColor:[UIColor whiteColor]];
[self.usernameField setTextAlignment:NSTextAlignmentCenter];
[self.usernameField setAutocapitalizationType:UITextAutocapitalizationTypeNone];
[self.usernameField setBorderStyle:UITextBorderStyleNone];
[self.usernameField setBackgroundColor:[UIColor clearColor]];
[self.usernameField setLeftViewMode:UITextFieldViewModeAlways];
self.usernameField.leftView = [[UIView alloc] init];
[self.usernameField.leftView setFrame:CGRectMake(0, 0, 50, 30)];
[self.usernameField.leftView setBackgroundColor:[UIColor clearColor]];
UIImageView *imgViewMail = [[UIImageView alloc] initWithFrame:CGRectMake(20, 5, 25, 25)];
[imgViewMail setImage:[UIImage imageNamed:@"mail_icon"]];
[self.usernameField.leftView addSubview:imgViewMail];
[self.view addSubview:self.usernameField];

编辑-说明问题的图像。-前两个文本字段

---

您可以创建自定义UITextField，并覆盖以下方法：

#pragma mark - Override UITextField

- (CGRect) textRectForBounds: (CGRect) bounds
{
  float x = bounds.origin.x + 50.f;
  float y = bounds.origin.y;
  float width  = bounds.size.width - (100.f);
  float height = bounds.size.height;

  return CGRectMake(x, y, width, height);
}

- (CGRect) editingRectForBounds: (CGRect) bounds
{
  return [self textRectForBounds: bounds];
}

---

您可以发布任何图像来确定确切的问题吗？k，因为您说电子邮件和senha应该居中右侧？它应该居中，向左多个像素。但是，它应该是

self.usernameField=[[UITextField alloc]…

而不是

self.usernameField=[[textfield自定义alloc]…

（自定义UITextField的名称）