iphone - UIPickerView 在选择器中消失的图像

Question

我正在尝试使用 UIPickerView 构建“老虎机”游戏。我使用 UIImageView 填充它。问题是，每次旋转后选择器 View 中的随机图像都会消失，然后再次随机显示。它发生在带有 ios 5.1.1 的设备上，但在带有 ios4.2.1 和模拟器的设备上它可以完美运行。现在我正在使用 CircularPickerView但在我使用 UIPickerView 之前，问题是一样的。这是屏幕截图:http://axgrzesiek.w.interii.pl/licznik.PNG

GraViewController.h:

#import <UIKit/UIKit.h>

#import "CircularPickerView.h"
@interface GraViewController : UIViewController
    <UIPickerViewDataSource, UIPickerViewDelegate> {
        CircularPickerView *picker;
        UILabel *winLabel;
        NSArray *column1;
        NSArray *column2;
        NSArray *column3;


}
@property(nonatomic, retain) IBOutlet CircularPickerView *picker;
@property(nonatomic, retain) IBOutlet UILabel *winLabel;
@property(nonatomic, retain) NSArray *column1;
@property(nonatomic, retain) NSArray *column2;
@property(nonatomic, retain) NSArray *column3;
-(IBAction)spin;

@end

GraViewController.m:

- (IBAction)spin { 
    BOOL win = NO;
    int numInRow = 1; 
    int lastVal = -1; 
    for (int i = 0; i < 3; i++) {
        int newValue = arc4random() % [self.column1 count];
        if (newValue == lastVal) 
            numInRow++;
        else
            numInRow = 1;

        lastVal = newValue; 
        //if (newValue < [self.column1 count] || newValue >= (2 * [self.column1 count]) ) {
            //newValue = newValue % [self.column1 count];
            //newValue += [self.column1 count];
        [self.picker selectRow:newValue inComponent:i animated:YES];


        //}
        NSLog(@"kol:%d %d",i, newValue);
        //[picker reloadComponent:i]; 
        if (numInRow >= 3)
            win = YES;
    } 
    if (win)
        winLabel.text = @"WIN!"; 
    else 
        winLabel.text = @"";

    //[picker reloadAllComponents];
    //[self performSelector:@selector(moveIntoPosition) withObject:nil afterDelay:0.5f];



- (void)viewDidLoad { 

    NSString  *title=@"Gra";
    [self setTitle:title];

    UIImage *seven = [UIImage imageNamed:@"jeden.png"]; 
    UIImage *bar = [UIImage imageNamed:@"dwa.png"]; 
    UIImage *crown = [UIImage imageNamed:@"trzy.png"]; 
    UIImage *cherry = [UIImage imageNamed:@"cztery.png"]; 
    UIImage *lemon = [UIImage imageNamed:@"piec.png"]; 
    UIImage *apple = [UIImage imageNamed:@"szesc.png"];
    for (int i = 1; i <= 3; i++) { 
        UIImageView *sevenView = [[UIImageView alloc] initWithImage:seven]; 
        UIImageView *barView = [[UIImageView alloc] initWithImage:bar]; 
        UIImageView *crownView = [[UIImageView alloc] initWithImage:crown]; 
        UIImageView *cherryView = [[UIImageView alloc] initWithImage:cherry]; 
        UIImageView *lemonView = [[UIImageView alloc] initWithImage:lemon];
        UIImageView *appleView = [[UIImageView alloc] initWithImage:apple]; 
        NSArray *imageViewArray = [[NSArray alloc] initWithObjects:
                                    sevenView, barView, crownView, cherryView, lemonView, appleView, nil];
        NSString *fieldName = [[NSString alloc] initWithFormat:@"column%d", i];
        [self setValue:imageViewArray forKey:fieldName];
        //column1=[[NSArray alloc]initWithArray:imageViewArray];
        //column2=[[NSArray alloc]initWithArray:imageViewArray];
        //column3=[[NSArray alloc]initWithArray:imageViewArray];
        [fieldName release];
        [imageViewArray release];
        [sevenView release]; 
        [barView release]; 
        [crownView release]; 
        [cherryView release]; 
        [lemonView release]; 
        [appleView release];
        //[picker selectRow: [self.column1 count] * (48 / 2) inComponent:i-1 animated:NO];
    }


}


- (UIView *)pickerView:(UIPickerView *)pickerView viewForRow:(NSInteger)row forComponent:(NSInteger)component reusingView:(UIView *)view {

    NSString *arrayName = [[NSString alloc] initWithFormat:@"column%d", component+1];
    NSArray *array = [self valueForKey:arrayName];
    [arrayName release];
    return [array objectAtIndex:row];

}

Answer 1

我认为问题可能出在您为选择器重用 View 的方式上——您不应该自己缓存 UIImageView(可能 UIPickerView 试图在多个地方使用相同的 UIImageView，所以其中一个地方没有被占用)。

正确的方法是存储 UIImage 实例并填充可能由选择器缓存的 UIImageView。样板代码(未测试):

- (void) viewDidLoad{
 ...
 Here cache UIImages, not UIImageViews
 ...
}

- (UIView *)pickerView:(UIPickerView *)pickerView viewForRow:(NSInteger)row forComponent:(NSInteger)component reusingView:(UIView *)view {

    NSString *arrayName = [[NSString alloc] initWithFormat:@"column%d", component+1];
    NSArray *array = [self valueForKey:arrayName];
    [arrayName release];
    UIImage *image = [array objectAtIndex:row];

    if (!view){
       view = [[[UIImageView alloc] init] autorelease];
    }
    [(UIImageView*)view setImage:image];
    return view;
}