ios - 无法在另一个类的自定义类上设置 UIImageView.image

Question

我有一个自定义类 A，它是 UIView 的子类，它本质上管理一个适合 View 大小的 UIScrollView 并且包含一个 UIImageView 填充那个 scrollView。

我在设置自定义类的 imageView.image 时遇到问题:

这是类

#import "BackgroundPickerView.h"

@implementation BackgroundPickerView

@synthesize scrollView;
@synthesize imageView;
@synthesize actionButton;

-(id)initWithFrame:(CGRect)frame
{
    self = [super initWithFrame:frame];

    return self;
}

-(void)layoutSubviews
{
    [super layoutSubviews];

    //[[NSNotificationCenter defaultCenter] addObserver:self
      //                                       selector:@selector(changeImage)
        //                                         name:@"ImageChangeNotification"
          //                                     object:nil];

    //Here's where we add custom subviews
    scrollView = [[UIScrollView alloc] init];
    imageView = [[UIImageView alloc] init];
    actionButton = [[UIButton alloc] init];

    [scrollView setFrame:CGRectMake(0, 0, 321, 115)];
    [imageView setFrame:CGRectMake(0, 0, 321, 115)];
    [actionButton setFrame:CGRectMake(0, 0, 320, 115)];

    scrollView.scrollEnabled = YES;
    scrollView.minimumZoomScale = 1.0;
    scrollView.maximumZoomScale = 6.0;
    scrollView.contentSize = CGSizeMake(300, 200);//imageView.image.size; 

    [scrollView addSubview:imageView];
    [self addSubview:scrollView];
}

-(void)storeImage:(UIImage *)image
{   
    self.imageView.image = image;
}

-(void)changeImage
{
    [self.imageView setImage:[UIImage imageNamed:@"random.png"]];
}

从我收到图像的其他 B 类中，我尝试使用 NSNotification 和一个简单的 setter 方法来尝试设置类对象的 imageView 属性，但似乎无法设置 imageView.image .我试过使用

instance.imageView.image = myImageToSet

//Setter
[instance storeImage:myImageToSet];

在 B 类中，但没有成功

Answer 1

首先，在 layoutSubviews 中初始化 subview 不是最好的方法，最好在 init 方法中初始化它们，因为 layoutSubviews可能会多次调用来布局 subview ，如果您将初始化代码放在 layoutSubviews 中，则可能会有 subview 。在 layoutSubviews 中，您只设置 subview 的 frame。

你可以像下面那样做，

 #import "BackgroundPickerView.h" 
 @implementation CustomViewA

 //Edit change below 

 - (id)initWithFrame:(CGRect)frame
  {
    self = [super initWithFrame:frame];
    if(self)
    {
     [self commonInit];
    }
    return self;
}

- (void)awakeFromNib
{
   [self commonInit];
}

 - (void)commonInit
 {
   _scrollView = [[UIScrollView alloc] init];
   _imageView = [[UIImageView alloc] init];
   _actionButton = [[UIButton alloc] init];

   _scrollView.scrollEnabled = YES;
   _scrollView.minimumZoomScale = 1.0;
   _scrollView.maximumZoomScale = 6.0;

   [_scrollView addSubview:_imageView];
   [self addSubview:_scrollView];
}

- (void)layoutSubviews
 {
   [super layoutSubviews];
   [_scrollView setFrame:CGRectMake(0, 0, 321, 115)];
   [_imageView setFrame:CGRectMake(0, 0, 321, 115)];
   [_actionButton setFrame:CGRectMake(0, 0, 320, 115)];

   _scrollView.contentSize = CGSizeMake(300, 200);
 }

 -(void)storeImage:(UIImage *)image
 {
    self.imageView.image = image;
 }

 -(void)changeImage
 {
   [self.imageView setImage:[UIImage imageNamed:@"random.png"]];
 }

synthesese 是可选的在 BackgroundPickerView.h 文件中，它类似于下面的内容

 @interface BackgroundPickerView : UIView
 @property (nonatomic, strong) UIScrollView *scrollView;
 @property (nonatomic, strong) UIImageView  *imageView;
 @property (nonatomic, strong) UIButton     *actionButton;

 -(void)storeImage:(UIImage *)image;
 -(void)changeImage;

对于图像你检查它应该工作，检查图像是否存在，

编辑对于图片，以controller为例，

- (void)viewDidLoad {
  [super viewDidLoad];
   // Do any additional setup after loading the view, typically from a nib.
   _viewA = [[BackgroundPickerView alloc] initWithFrame:self.view.bounds];
   [self.view addSubview:_viewA];
 }

 //for testing 
 - (void)viewDidAppear:(BOOL)animated
 {
    [super viewDidAppear:animated];
    [_viewA storeImage:[UIImage imageNamed:@"6.png"]]; //hear do this
 }