Xcode：使文本字段显示选择器视图或下拉菜单

Question

有人可以提供一些示例代码，说明如何在 iOS 应用程序上创建以下功能：

选项 1： 我想通过 Interface Builder 创建一个文本字段，当有人单击该文本字段时，我希望它不显示默认键盘，而是显示一个选择器视图，其中列出了我喜欢的几个选项。用户完成选择某个值后，他们可以单击选择器视图旁边的“完成”按钮，选择器视图将消失，文本字段将填充他们在选择器视图上选择的内容。

选项 2 如果前面的方法需要太多代码才能完成，有人可以提供有关如何创建类似于网站上标准下拉菜单的基本下拉菜单的示例代码吗？

谢谢

Answer 1

创建一个新文件。我调用了我的 AEMPicker。 .h:

@protocol AEMPickerDelegate <NSObject>

-(void)touchedPicker:(NSString *)string;

@optional
-(void)setInitialPickerValueToRow:(int)i inComponent:(int)j animated:(BOOL)k;

@end

@interface AEMPicker : UIViewController <UIPickerViewDataSource, UIPickerViewDelegate>{
    UIPickerView *pickerView;
}
@property (nonatomic, strong) NSArray *contentArray;
@property (nonatomic, assign) id<AEMPickerDelegate> delegatePicker;

- (id)initWithArray:(NSArray *)contents inFrame:(CGRect)pickerFrame;
@end

.m:

#import "AEMPicker.h"

@implementation AEMPicker

@synthesize contentArray;
@synthesize delegatePicker;

- (id)initWithArray:(NSArray *)contents inFrame:(CGRect)pickerFrame
{
    self = [super init];
    if (self) {
        contentArray = [NSArray arrayWithArray: contents];

        pickerView = [[UIPickerView alloc] initWithFrame:pickerFrame];
        pickerView.showsSelectionIndicator = YES;
        pickerView.delegate = self;

        [self.view addSubview:pickerView];
    }
    return self;
}
-(void)setInitialPickerValueToRow:(int)i inComponent:(int)j animated:(BOOL)k{
    [pickerView selectRow:i inComponent:j animated:k];
}

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

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

- (NSString *)pickerView:(UIPickerView *)thePickerView titleForRow:(NSInteger)row forComponent:(NSInteger)component {
    return [contentArray objectAtIndex:row];
}

- (void)pickerView:(UIPickerView *)thePickerView didSelectRow:(NSInteger)row inComponent:(NSInteger)component {
    [self.delegatePicker touchedPicker:[contentArray objectAtIndex:row]];
}

@end

现在，在你想要展示你的 pickerView 的类中，在 #import AEMPicker; 添加到你的 .h:

@interface YourClass : UIViewController <AEMPickerDelegate, UITextFieldDelegate>{
AEMPicker *picker;
UIPopoverController *pickerPopOver;
UIPopoverController *pOC;
CGRect popRect;
}

添加到你的 .m:

- (void)textFieldDidBeginEditing:(UITextField *)textField
{
    [textField resignFirstResponder];

    popRect = CGRectMake(406, 110, 0, 0);
    CGRect pickerRect = CGRectMake(0, 10, 0, 0);

    NSArray *contents = [[NSArray alloc] initWithObjects:@"Object 1", @"Object 2", @"Object 3", nil];
    picker = [[AEMPicker alloc] initWithArray:contents inFrame:pickerRect];
    picker.delegatePicker = self;

    pickerPopOver = [[UIPopoverController alloc] initWithContentViewController:picker];
    pickerPopOver.popoverContentSize = CGSizeMake(320, 250);
    [pickerPopOver presentPopoverFromRect:popRect inView:self.view permittedArrowDirections:UIPopoverArrowDirectionAny animated:TRUE];

        pOC = pickerPopOver;
}

-(void)touchedPicker:(NSString *)string{

    [yourTextField setText:string];
    [pickerPopOver dismissPopoverAnimated:YES];
}

- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation
{
    [pOC dismissPopoverAnimated:NO];
    return YES;
}

这应该会给你一个漂亮的可以使用的基本选择器弹出窗口。