无法让这个警报实例显示在这个实现文件中，我就是找不到问题所在。
其他一切正常。
关于有什么问题的任何建议？
#import "BIDSingleComponentViewController.h"
@implementation BIDSingleComponentViewController
- (IBAction)buttonPressed
{
NSInteger row = [self.singlePicker selectedRowInComponent:0];
NSString *selected = self.characterNames[row];
NSString *title = [[NSString alloc] initWithFormat:@"You selected %@", selected];
UIAlertView *alert = [[UIAlertView alloc] initWithTitle:title
message:@"Thank you for choosing."
delegate:nil
cancelButtonTitle:@"You're welcome."
otherButtonTitles: nil];
[alert show];
}
- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
if (self) {
// Custom initialization
}
return self;
}
- (void)viewDidLoad
{
[super viewDidLoad];
// Do any additional setup after loading the view from its nib.
self.characterNames = @[@"Luke", @"Leia", @"Han", @"Chewbacca", @"Artoo", @"Threepio", @"Lando"];
}
- (void)didReceiveMemoryWarning
{
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
#pragma mark
#pragma mark Picker Data Source Methods
- (NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerView
{
return 1; // Incompatible integer to pointer conversion
}
- (NSInteger)pickerView:(UIPickerView *)pickerView numberOfRowsInComponent:(NSInteger)component
{
return [self.characterNames count];
}
#pragma mark Picker Delegate Methods
-(NSString *)pickerView:(UIPickerView *)pickerView titleForRow:(NSInteger)row forComponent:(NSInteger)component
{
return self.characterNames[row];
}
@end
头文件：
#import <UIKit/UIKit.h>
@interface BIDSingleComponentViewController : UIViewController
<UIPickerViewDelegate, UIPickerViewDataSource>
@property (strong, nonatomic)IBOutlet UIPickerView *singlePicker;
@property (strong, nonatomic)NSArray *characterNames;
- (IBAction)buttonPressed;
@end