UIView在NSCache被覆盖

Question

我有一个UIView包含投影阴影和角落，我正在加载我的UIViewController中的四个，并且我看到屏幕加载时性能下降。由于我使用的阴影和角半径相同的白色背景，我想我会将UIView存储在NSCache中。

当我运行的应用程序有一个很大的差距，第一个UIView应该是，但它没有显示出来。显示的是我的视图列表中的最后一个视图。如果我将最后一个注释掉并再次运行，第三个显示出来。这似乎是我在内存中的指针有问题，但不知道。也许我错误地使用了NSCache？

（注：不使用NSCache显示的第一个视图）

这里是我如何使用NSCache：

.h文件中

@interface LunchDetailViewController : UIViewController <UIScrollViewDelegate> 

@property (nonatomic) IBOutlet UIScrollView *scrollView; 
@property (nonatomic, strong) NSCache *entreeViewsCache; 

@end 

.m文件

@synthesize scrollView; 
@synthesize entreeViewsCache; 

- (void)viewDidLoad 
{ 
    [super viewDidLoad]; 

    self.entreeViewsCache = [[NSCache alloc] init]; 
    UIView *entreeView = [[UIView alloc] init]; 
    entreeView.backgroundColor = [UIColor whiteColor]; 
    entreeView.layer.masksToBounds = NO; 
    entreeView.layer.cornerRadius = 3.0; 
    entreeView.layer.shadowOffset = CGSizeMake(1.1, 2.1); 
    entreeView.layer.shadowOpacity = 0.2; 

    [self.entreeViewsCache setObject:entreeView forKey:@"EntreeView"]; 
} 

- (void) configureScrollView 
{ 
    // This line of code allows the scroll view to be 'scrollable'. 
    self.scrollView.contentSize = CGSizeMake(320, 620); 

    UIView *elementaryRoundedCornerView = [self.entreeViewsCache objectForKey:@"EntreeView"]; 
    elementaryRoundedCornerView.frame = CGRectMake(15,15,290,180); 

    UIView *middleRoundedCornerView = [self.entreeViewsCache objectForKey:@"EntreeView"]; 
    middleRoundedCornerView.frame = CGRectMake(15,210,290,180); 

    UIView *highRoundedCornerView = [self.entreeViewsCache objectForKey:@"EntreeView"]; 
    highRoundedCornerView.frame = CGRectMake(15,404,290,180); 

    NSMutableArray *entreeItems = [[NSMutableArray alloc] initWithObjects:@"Pancakes w/ Sausage Patties", @"Corn Dog", @"Grilled Cheese Sandwhich", @"Chicken Tender Wraps", nil]; 


    UIView *elementaryLunchMenuDetails = [[UIView alloc] initWithFrame:CGRectMake(10, 10, 240, 160)]; 
    [elementaryLunchMenuDetails addSubview:[self returnNativeCode:entreeItems rectDimensions:CGRectMake(2, 5, 215, 160) schoolType:@"Elementary"]]; 
    [elementaryRoundedCornerView addSubview:elementaryLunchMenuDetails]; 

    UIView *middleLunchMenuDetails = [[UIView alloc] initWithFrame:CGRectMake(10, 10, 240, 160)]; 
    [middleLunchMenuDetails addSubview:[self returnNativeCode:entreeItems rectDimensions:CGRectMake(2, 2, 215, 160) schoolType:@"Middle"]]; 
    [middleRoundedCornerView addSubview:middleLunchMenuDetails]; 

    UIView *highLunchMenuDetails = [[UIView alloc] initWithFrame:CGRectMake(10,10, 240, 160)]; 
    [highLunchMenuDetails addSubview:[self returnNativeCode:entreeItems rectDimensions:CGRectMake(2, 2, 215, 160) schoolType:@"High"]]; 
    [highRoundedCornerView addSubview:highLunchMenuDetails]; 

    [self.scrollView addSubview:elementaryRoundedCornerView]; 
    [self.scrollView addSubview:middleRoundedCornerView]; 
    [self.scrollView addSubview:highRoundedCornerView]; 
} 

Answer 1

哇。这很聪明。但不正确。

而不是使用NSCache复制视图，您可能需要创建一个UIView子类，以您想要的方式设置视图的格式。然后在你的滚动视图上扔一堆视图。

ABCView.m

@implementation ABCDayView 

- (id)initWithFrame:(CGRect)frame 
{ 
    self = [super initWithFrame:frame]; 
    if (self) { 
     self.backgroundColor = [UIColor whiteColor]; 
     self.layer.masksToBounds = NO; 
     self.layer.cornerRadius = 3.0; 
     self.layer.shadowOffset = CGSizeMake(1.1f, 2.1f); 
     self.layer.shadowOpacity = 0.2f; 
    } 
    return self; 
} 

- (void)setItems:(NSArray *)items 
{ 
    if ([_items isEqualToArray:items] == NO) { 
     _items = items; 
     [self createItemViews]; 
     [self setNeedsLayout]; 
    } 
} 

// You'll also need to add -createItemViews and -setNeedsLayout methods. 

.m文件

- (void)configureScrollView 
{ 
    NSMutableArray *entreeItems = @[@"Pancakes w/Sausage Patties", 
            @"Corn Dog", 
            @"Grilled Cheese Sandwhich", 
            @"Chicken Tender Wraps"]; 

    CGRect frame = CGRectMake(15,15,290,180); 
    ABCDayView *elementaryView = [[ABCDayView alloc] initWithFrame:frame]; 
    elementaryView.items = entreeItems; 

    CGFloat y = CGRectGetMaxY(elementaryView.frame) + 10.0f; 
    frame = CGRectMake(15, y, 290, 180); 
    ABCDayView *middleView = [[ABCDayView alloc] initWithFrame:frame]; 
    middleView.items = entreeItems; 

    ... 

    CGFloat length = // Use CGRectGetMaxY on the last frame to get the length. 
    self.scrollView.contentSize = CGSizeMake(320, length); 
} 

这绝不是完美的代码。但希望它会给你一个更好的实现方法的想法。