UITextField对象的手工创建
1.UITextField的初始化和设置

UITextField *textField = [[UITextField alloc] initWithFrame:CGRectMake(10, 200, 300, 40)];
textField.borderStyle = UITextBorderStyleRoundedRect;
textField.font = [UIFont systemFontOfSize:15];
textField.placeholder = @"enter text";
textField.autocorrectionType = UITextAutocorrectionTypeNo;
textField.keyboardType = UIKeyboardTypeDefault;
textField.returnKeyType = UIReturnKeyDone;
textField.clearButtonMode = UITextFieldViewModeWhileEditing;
textField.contentVerticalAlignment = UIControlContentVerticalAlignmentCenter;
textField.delegate = self;
[self.view addSubview:textField];
[textField release];

2.要实现的Delegate方法,打开或关闭键盘

显示keyboard:
[textField becomeFirstResponder];
- (BOOL)textFieldShouldBeginEditing:(UITextField *)textField
{
[textField becomeFirstResponder];
return YES;
}

隐藏keyboard
[textField resignFirstResponder];

- (BOOL)textFieldShouldReturn:(UITextField *)textField
{
[textField resignFirstResponder];
return YES;
}