UIPickerView消失在選取器內的圖像

Question

我試圖用UIPickerView建立「老虎機」遊戲。我使用UIImageView填充它。問題在於，每次旋轉後，拾取器視圖中的隨機圖像都會消失，並隨機再次顯示。它發生在使用ios 5.1.1的設備上，但是在使用ios4.2.1和模擬器的設備上它完美地工作。現在我使用的是CircularPickerView，但在使用UIPickerView之前，問題是一樣的。 下面是截圖：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

我想問題可能是你的看法重用你的選擇器的方式 - 你不應該自己緩存UIImageViews（可能UIPickerView會嘗試在多個地方使用相同的UIImageView，因此其中一個地方未被佔用）。

正確的方法是存儲UIImage實例並填充可能被picker緩存的UIImageView。樣板代碼（未經測試）：

- (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; 
}