如何将UIImages数组添加到集合视图

Question

提前感谢您查看此项目并向我伸出援助之手。

故事板连接

我正在尝试在Collection View中显示一组UIImages。我已连接故事板中的所有内容。
我的ViewController既是我的Collection View的委托和dataSource。
我的单元格包含一个UIImageView，它在我的自定义单元格的头文件中有一个IBOutlet。

应用目前如何运作

1. 该应用程序基于a从维基百科API创建一系列图像 用户搜索。
2. 一旦用户输入他或她的搜索，ViewController就会通过 NSString关闭到模型（GetImageURL.h和GetImageURL.m。）
3. 这似乎是基于我正在使用的NSLog。
4. 模型设置完成后，模型会将其传回控制器 UIImages数组。
5. ViewController然后尝试重新加载collectionView的数据和 应用程序崩溃。

错误消息如下所示：

*** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: 'UICollectionView must be initialized with a non-nil layout parameter'
*** First throw call stack: 
(0x1c97012 0x10d4e7e 0x1c96deb 0x518748 0x533b1b 0x533646 0xf9ff8 0xfa232 0x5338d5 0x29a4 0x3ef6 0xb13fb4 0xb13e67 0x30ca 0x49fb53f 0x4a0d014 0x49fd7d5 0x1c3daf5 0x1c3cf44 0x1c3ce1b 0x1bf17e3 0x1bf1668 0x18ffc 0x1b9d 0x1ac5)
libc++abi.dylib: terminate called throwing an exception




我的问题

我想知道我在创建collectionView时遇到了什么错误，导致它在稍后调用reloadData时崩溃。


代码

ViewController.h

#import <UIKit/UIKit.h>

@interface ViewController : UICollectionViewController <UICollectionViewDelegateFlowLayout, UICollectionViewDataSource, UIApplicationDelegate>

//receives a mutable array of UIImage(s)
-(void)receiveArrayOfImages: (NSMutableArray *)arrayOfImages;
@end


ViewController.m

#import "ViewController.h"
#import "Cell.h"
#import "GetImageURL.h"

NSString *kCellID = @"cellID";

@interface ViewController () {
    UISearchBar *searchBar;
}
@property (nonatomic, strong) NSString *searchBarText;
@property (strong, nonatomic) NSMutableArray *arrayOfImages;

@end

@implementation ViewController

-(NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section {
    if ([self.arrayOfImages count] > 0) {
        NSLog(@"return %d items for collection view", [self.arrayOfImages count]);
        return [self.arrayOfImages count];
    } else {
        NSLog(@"returned 0 items for collection view");
        return 0;
    }
}

- (UICollectionViewCell *)collectionView:(UICollectionView *)cv cellForItemAtIndexPath:(NSIndexPath *)indexPath {

    NSLog(@"cellForItemAtIndexPath");

    Cell *cell = [cv dequeueReusableCellWithReuseIdentifier:kCellID forIndexPath:indexPath];
    int row = [indexPath row];
    cell.cellImage.image = [self.arrayOfImages objectAtIndex:row];
    return cell;
}

- (void)viewDidLoad
{
    [super viewDidLoad];
    //Creates a Search Bar Button System Item.
    UIBarButtonItem *searchButton = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemSearch target:self action:@selector(tapSearchButton:)];
    self.navigationItem.rightBarButtonItem = searchButton;
}


-(void)tapSearchButton:(id)sender {
    //Adds or takes away searchbar on navigationbar.
    if (!searchBar) {
        searchBar = [[UISearchBar alloc] initWithFrame:CGRectMake(-5.0, 0.0, 320.0, 44.0)];
        searchBar.autoresizingMask = UIViewAutoresizingFlexibleWidth;
        UIView *searchBarView = [[UIView alloc] initWithFrame:CGRectMake(0.0, 0.0, 310.0, 44.0)];
        searchBarView.autoresizingMask = 0;
        searchBar.delegate = self; //this line causes a warning. "Assigning to 'id<UISearchBarDelegate> from incompatible type 'ViewController *cons_strong"
        [searchBarView addSubview:searchBar];
        self.navigationItem.titleView = searchBarView;
        [searchBar becomeFirstResponder];
    } else {
        self.navigationItem.titleView = nil;
        searchBar = nil;
    }
}

- (void)searchBarSearchButtonClicked:(UISearchBar *)searchBar {
    GetImageURL *bookName = [[GetImageURL alloc] init];
    bookName.bookName = [searchBar text]; //this line causes a warning. "Local declaration of 'searchBar' hides instance variable"
    NSLog(@"In ViewController, the book name is: %@", bookName.bookName);
    [bookName recieveBookUrl:bookName.bookName];
    [self.view endEditing:YES];
}

-(void)receiveArrayOfImages: (NSMutableArray *)arrayOfImages {
    //receives an array of UImages called arrayOfImages and sets it to self.arrayOfImages
    self.arrayOfImages = arrayOfImages;
    NSLog(@"This is the array of UIimages in ViewController.m: %@", self.arrayOfImages);

    [self.collectionView reloadData]; //This line causes the app the crash. "Reason: UICollectionView must be initialized with a non-nil layout parameter"
}

@end


Cell.h

#import <UIKit/UIKit.h>

@interface Cell : UICollectionViewCell

//UIImageView inside Custom Cell
@property (strong, nonatomic) IBOutlet UIImageView *cellImage;

@end


Cell.m

#import "Cell.h"

@implementation Cell

- (id)initWithCoder:(NSCoder *)coder
{
    self = [super initWithCoder:coder];
    if (self) {
    }
    return self;
}

@end


GetImageURL.h

#import <Foundation/Foundation.h>
#import "ViewController.h"

@interface GetImageURL : NSObject

@property (strong, nonatomic) NSString *bookName;
@property (strong, nonatomic) NSMutableArray *imageArray;

-(void)recieveBookUrl:(NSString *)bookName; //recieves a string from the viewController that the user inputs

@end


GetImageURL.m

#import "GetImageURL.h"

@interface GetImageURL()

@property (strong, nonatomic) NSString *pageID;
@property (strong, nonatomic) NSMutableArray *imageUrlArray;

@end


@implementation GetImageURL

//takes the string that the user entered and alters it to fit the wikipedia API format
-(void)recieveBookUrl:(NSString *)bookName {
    self.imageUrlArray = [[NSMutableArray alloc] init];
    self.imageArray = [[NSMutableArray alloc] init];
    bookName = [bookName stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding]; //or use string by replacing @" " with @"%20";
    NSString *wikiAPI  = @"http://en.wikipedia.org/w/api.php?format=json&indexpageids&action=query&prop=images&titles=";
    bookName = [wikiAPI stringByAppendingString:bookName];
    NSURL *bookURL = [NSURL URLWithString:bookName];
    //Plan to put this action in the background later
    dispatch_async(dispatch_get_main_queue(), ^() {
        NSData *data = [NSData dataWithContentsOfURL:bookURL];
        [self performSelectorOnMainThread:@selector(getBookTitleApi:) withObject:data waitUntilDone:YES];
    });
}

//first part of the API sucessfully gets the padeID and all the images returned by the API.
-(void)getBookTitleApi: (NSData *)data {
    NSError *error;
    NSDictionary *json = [NSJSONSerialization
                          JSONObjectWithData:data
                          options:kNilOptions
                          error:&error];
    NSDictionary *parseQueryBookTitle = [json objectForKey:@"query"];
    NSArray *parsePageIdsBookTitle = [parseQueryBookTitle objectForKey:@"pageids"];
    for (NSDictionary *pageIdBookTitle in parsePageIdsBookTitle) {
        self.pageID = [NSString stringWithFormat:@"%@", pageIdBookTitle];
    }

    NSDictionary *parsePagesBookTitle = [parseQueryBookTitle objectForKey:@"pages"];
    NSDictionary *parsePageIdBookTitle = [parsePagesBookTitle objectForKey:self.pageID];
    NSDictionary *parseImagesBookTitle = [parsePageIdBookTitle objectForKey:@"images"];
    NSDictionary *valueTitleBookTitle = [parseImagesBookTitle valueForKey:@"title"];

    for (NSDictionary *imageFilenames in valueTitleBookTitle) {
        NSString *imageFilename = [NSString stringWithFormat:@"%@", imageFilenames];
        imageFilename = [imageFilename substringFromIndex:5];
        imageFilename = [imageFilename stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding]; //or use string by replacing @" " with @"%20";

        NSString *wikiImageAPI = @"http://en.wikipedia.org/w/api.php?action=query&format=json&indexpageids&prop=imageinfo&iiprop=url&titles=Image:";
        imageFilename = [wikiImageAPI stringByAppendingString:imageFilename];

        NSURL *imageFilenameUrl = [NSURL URLWithString:imageFilename];
        NSData *data = [NSData dataWithContentsOfURL:imageFilenameUrl];
        [self performSelectorOnMainThread:@selector(getImageApi:) withObject:data waitUntilDone:YES];
    }
    //Uses the URLs to create an NSData object and then uses that data to create a UIImage which is added to a Mutable Array
    for (NSString *jpgURL in self.imageUrlArray) {
        NSURL *imageURL = [NSURL URLWithString:jpgURL];
        NSLog(@"This is an imageURL in GetImageURL.m: %@", imageURL);
        NSData *data = [NSData dataWithContentsOfURL:imageURL];
        UIImage *image = [UIImage imageWithData:data];
        [self.imageArray addObject:image];
    }


    NSLog(@"The array of images in GetImageURL.m contains %d images called %@", [self.imageArray count], self.imageArray);
    ViewController *view = [[ViewController alloc] init];
    [view receiveArrayOfImages:self.imageArray]; //sends the array of images to the View Controller

    //objects removed from array so that next user search can start over
    [self.imageArray removeAllObjects];
    [self.imageUrlArray removeAllObjects];
}

//Uses the image filenames from the first section and gets the specific URLS for the image. Limits results to .jpg images
-(void)getImageApi: (NSData *)data {
    NSError *error;
    NSDictionary *json = [NSJSONSerialization JSONObjectWithData:data options:kNilOptions error:&error];

    NSDictionary *parseQueryImage = [json objectForKey:@"query"];
    NSDictionary *parsePageIdsImage = [parseQueryImage objectForKey:@"pageids"];

    for (NSString *pageIdImage in parsePageIdsImage) {
        NSDictionary *parsePagesImage = [parseQueryImage objectForKey:@"pages"];
        NSDictionary *parsePageIdImage = [parsePagesImage objectForKey:pageIdImage];
        NSDictionary *parseImageInfoImage = [parsePageIdImage objectForKey:@"imageinfo"];
        NSDictionary *valueImageInfoUrlsImage = [parseImageInfoImage valueForKey:@"url"];

        for (NSString *valueImageInfoUrlImage in valueImageInfoUrlsImage) {

            if ([valueImageInfoUrlImage hasSuffix:@".jpg"]) {
                [self.imageUrlArray addObject:valueImageInfoUrlImage];
            }
        }
    }
}

@end




很抱歉在这里转储所有代码。我认为如果它就在那里会更容易。也许它对别人也有帮助。

谢谢！

Answer 1

您的布局是否设置为流量？它应该在你的故事板中看起来像这样：

如果将其设置为自定义，则需要自己创建布局。

Answer 2

如果您的集合视图单元格未在故事板中创建，那么我认为您必须注册它。

如果您的细胞已编程

// Add this in your controller's viewDidLoad method
[self.collectionView registerClass:[UICollectionViewCell class] forCellWithReuseIdentifier:kCellID];

如果您的单元格有一个nib文件，我认为它是registerNib：forCellWithReuseIdentifier：

Answer 3

-(NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section{
    return array.count;
}
- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath{

    static NSString *identifier = @"Cell";
    UIImage *smallimage = [UIImage imageNamed:[NSString StringWithFormat:@"%@.png"[array[indexpath]]];

      UICollectionViewCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:identifier forIndexPath:indexPath];

    UIImageView *gridimageview = (UIImageView *)[cell viewWithTag:100];
    [gridimageview setImage:smallimage];
    return cell;

}
- (void)collectionView:(UICollectionView *)collectionView didSelectItemAtIndexPath:(NSIndexPath *)indexPath{
    NSLog(@"index path is %d", indexPath.row);
   //Enter the action you want when an image is clicked in collection view
    }
- (void)collectionView:(UICollectionView *)collectionView didDeselectItemAtIndexPath:(NSIndexPath *)indexPath{
//    Write your code here to  deselect the selected image
    }
}