拉起自定义UIPickerView的UITextField inputview属性出现问题

我一直无法从textfield的inputview属性中提取自定义UIPickerView . 我已经研究了一段时间，做了一些研究，并尝试将基于Apple的UICatalog示例的单独项目组合在一起 .

但是，每当我点击文本区域内的所有内容时，我都会看到一个黑色的屏幕，而不是选择器视图 . 我确定我已经忽略了一些东西，但我一直在寻找任何帮助将被赞赏的日子 .

请记住，这是我的测试项目，看看我是否可以将此功能添加到我的其他应用程序以及我尝试从UICatalog应用程序复制的许多代码 . 对不起，如果没有任何意义，请随时提出任何问题 . 谢谢 .

//  ViewController.h
//  TestPicker

#import <UIKit/UIKit.h>

@interface ViewController : UIViewController<UITextFieldDelegate,UIPickerViewDelegate,UIPickerViewDataSource>{

UIPickerView *picker;
     //The picker view the textfield responds to.

IBOutlet UITextField *myText;
     //The textfield which has the input view of a picker.

NSArray *testArray;
     //The array which values are loaded into the picker.
}

@end


//  ViewController.m
//  TestPicker


#import "ViewController.h"

@interface ViewController ()

@end

@implementation ViewController

- (void)viewDidLoad
{
    picker.delegate=self;
    picker.dataSource=self;
    myText.delegate=self;

    [self createPicker];

    [super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
}

- (void)viewDidUnload
{
    myText = nil;
    [super viewDidUnload];
    // Release any retained subviews of the main view.
}

- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation
{
    if ([[UIDevice currentDevice] userInterfaceIdiom] == UIUserInterfaceIdiomPhone) {
        return (interfaceOrientation != UIInterfaceOrientationPortraitUpsideDown);
    } 
    else {
        return YES;
    }
}

-(BOOL)textFieldShouldBeginEditing:(UITextField *)textField{
    picker = [[UIPickerView alloc] initWithFrame:CGRectZero];
    myText.inputView=picker;
    return YES;
}

-(void)textFieldDidBeginEditing:(UITextField *)textField{

}


- (NSString *)pickerView:(UIPickerView *)pickerView titleForRow:(NSInteger)row forComponent:(NSInteger)component
{
    NSString *returnStr = @"";

    if (pickerView == picker)
    {
        if (component == 0)
        {
            returnStr = [testArray objectAtIndex:row];
        }
        else
        {
            returnStr = [[NSNumber numberWithInt:row] stringValue];
        }
    }

    return returnStr;
}

- (NSInteger)pickerView:(UIPickerView *)pickerView numberOfRowsInComponent:(NSInteger)component
{
    return [testArray count];
}

- (NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerView
{
    return 1;
}


- (void)createPicker
{
    testArray = [NSArray arrayWithObjects:
                            @"John Appleseed", @"Chris Armstrong", @"Serena Auroux",
                            @"Susan Bean", @"Luis Becerra", @"Kate Bell", @"Alain Briere",
                        nil];


    picker = [[UIPickerView alloc] initWithFrame:CGRectZero];


    picker.showsSelectionIndicator = YES;   // note this is default to NO

    picker.delegate = self;
    picker.dataSource = self;

}

@end