Textfield首行缩进 光标颜色 清除按钮样式

首行缩进可以利用textfield的leftView做事

UILabel *usernameLeftView = [[UILabel alloc] initWithFrame:CGRectMake(0.f, 0.f, 10.f, 0.f)];
    usernameLeftView.backgroundColor = [UIColor clearColor];
    textField.leftView = usernameLeftView;

光标颜色：textField.tintColor = [UIColor blackColor];

清除样式：textField.clearButtonMode = UITextFieldViewModeWhileEditing;（常用方法）

typedef NS_ENUM(NSInteger, UITextFieldViewMode) {
    UITextFieldViewModeNever,／／从不
    UITextFieldViewModeWhileEditing,／／编辑时
    UITextFieldViewModeUnlessEditing,／／不在编辑状态时
    UITextFieldViewModeAlways／／总是
};

最终样式：加了边框的