从JSON中将缩略图图像加载到UITableView中

我遇到了尝试从JSON加载缩略图到UITableView单元格的问题。单元格的UI是一个xib文件。我无法解析JSON的缩略图部分并将其显示在表格视图中。自从我做到这一点以来（我倾向于在比典型的iOS应用程序更多的游戏上工作），而最后一次我做的是稍微不同的实现。从JSON中将缩略图图像加载到UITableView中

JSON：

{ 
    "data" : 
    [ 

    { 
     "user_id" : "3", 
     "username" : "Alex Perez", 
     "avatar_url" : "http://mywebsite.com/images/alex_avatar.png", 
     "message" : "Hello there?" 
    }, 
    { 
     "user_id" : "4", 
     "username" : "Jon Doe", 
     "avatar_url" : "http://mywebsite.com/images/john_avatar.png", 
     "message" : "I'm here now" 
    }, 
    { 
     "user_id" : "2", 
     "username" : "Sam Givens", 
     "avatar_url" : "http://mywebsite.com/images/sam_avatar.png", 
     "message" : "Can we have a meeting around 2?" 
    }, 

....

而且在Data.h数据：

#import <Foundation/Foundation.h> 

@interface Data : NSObject 

@property (nonatomic, readwrite) int user_id; 
@property (nonatomic, strong) NSString *username; 
@property (nonatomic, strong) NSString *avatar_url; 
@property (nonatomic, strong) NSString *message; 

- (void)loadWithDictionary:(NSDictionary *)dict; 
@end

Data.m：

#import "Data.h" 

@implementation Data 


- (void)loadWithDictionary:(NSDictionary *)dict { 

    self.user_id = [[dict objectForKey:@"user_id"] intValue]; 
    self.username = [dict objectForKey:@"username"]; 
    self.avatar_url = [dict objectForKey:@"avatar_url"]; 
    self.message = [dict objectForKey:@"message"]; 
} 

@end

这里宣布时，我遇到的问题该属性并将属性分配给数据，然后可以将其传递给要显示它的View Controller。我得到的编译器警告不兼容的指针类型分配给来自NSString *的UIImage *。我不明白为什么Xcode不会抱怨UILabel和UITextView等其他属性。

Cell.m

#import "Cell.h" 

@interface Cell() 

@property (nonatomic) int userID; 
// UIImageView property created from Interface Builder 
@property (strong, nonatomic) IBOutlet UIImageView *avatarImage; 
@property (nonatomic, strong) IBOutlet UILabel *usernameLabel; 
@property (nonatomic, strong) IBOutlet UITextView *messageTextView; 
@end 

@implementation Cell 


- (void)loadWithData:(Data *)data { 

    self.userID = data.user_id; 
    // Here I get "Incompatible pointer types assigning to UIImage * from NSString* 
    self.avatarImage.image = data.avatar_url; 
    self.usernameLabel.text = data.username; 
    self.messageTextView.text = data.message; 
} 
@end

最后它显示MessagesViewController：

@interface MessagesViewController() 

@property (nonatomic, strong) IBOutlet UITableView *tableView; 
@property (nonatomic, strong) NSMutableArray *loadedChatData; 
@end 

@implementation MessagesViewController 

- (void)viewDidLoad { 
    [super viewDidLoad]; 

    self.loadedChatData = [[NSMutableArray alloc] init]; 
    [self loadJSONData]; 
} 

- (void)loadJSONData { 

NSString *filePath = [[NSBundle mainBundle] pathForResource:@"data" ofType:@"json"]; 

NSError *error = nil; 

NSData *rawData = [NSData dataWithContentsOfFile:filePath options:NSDataReadingMappedIfSafe error:&error]; 

id JSONData = [NSJSONSerialization JSONObjectWithData:rawData options:NSJSONReadingAllowFragments error:&error]; 

[self.loadedChatData removeAllObjects]; 

if ([JSONData isKindOfClass:[NSDictionary class]]) { 

    NSDictionary *jsonDict = (NSDictionary *)JSONData; 

    NSArray *loadedArray = [jsonDict objectForKey:@"data"]; 
    if ([loadedArray isKindOfClass:[NSArray class]]) 
    { 
     for (NSDictionary *chatDict in loadedArray) 
     { 
      Data *chatData = [[Data alloc] init]; 
      [chatData loadWithDictionary:chatDict]; 
      [self.loadedChatData addObject:chatData]; 
     } 
     } 
    } 

    [self.tableView reloadData]; 
} 

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath { 

static NSString *cellIdentifier = @"Cell"; 
Cell *cell = nil; 

if (cell == nil) { 
    NSArray *nib = [[NSBundle mainBundle] loadNibNamed:cellIdentifier owner:self options:nil]; 
    cell = (Cell *)[nib objectAtIndex:0]; 
    } 

    Data *data = [self.loadedChatData objectAtIndex:[indexPath row]]; 

[cell loadWithData:data]; 

return cell; 
}

来源

2015-03-19 Paul

你必须修改错误行并将其用作：

self.avatarImage.image = [UIImage imageWithData:[NSData dataWithContentsOfURL:[NSURL URLWithString:data.avatar_url]]];

来源

2015-03-19 05:22:06

这就是它！我之前发现了类似的解决方案，但无法正常工作。 – Paul 2015-03-19 05:26:12

由于可能会有很多头像，因此一次可能需要一段时间才能加载所有图像。您可以使用[AsyncImageView]（https://github.com/nicklockwood/AsyncImageView/tree/master/Examples）进行图片加载。而且更简单[SDWebImage]（https://github.com/rs/SDWebImage）。 :) – 2015-03-19 05:36:26

的笔尖创建一个自定义类，然后将某些代码它加载从直接图像URL ...这个作品

var stringUrl = "http://mywebsite.com/images/alex_avatar.png" 
var url: NSURL = NSURL(string: stringUrl)!; 
self.imageView1.sd_setImageWithURL(url, placeholderImage: UIImage(named: "no_image_small.png"));

来源

2015-03-19 05:21:15

这是快速只是在Obj-C使用相同的技术 – 2015-03-19 05:21:44

尝试下面的代码，它可能会帮助你。

NSURL *url = [NSURL URLWithString:@"http://mywebsite.com/images/alex_avatar.png"]; 
    UIImage *thumbnail = [UIImage imageWithData: [NSData dataWithContentsOfURL:url]]; 
    if (thumbnail == nil) { 
     thumbnail = [UIImage imageNamed:@"noimage.jpg"] ; //if no image get from url mean show a dummy one 
    } 
    CGSize itemSize = CGSizeMake(80, 80);   //your own size can replace with 80 
    UIGraphicsBeginImageContext(itemSize); 
    CGRect imageRect = CGRectMake(0.0, 0.0, itemSize.width, itemSize.height); 
    [thumbnail drawInRect:imageRect]; 
    cell.thumbnailImageView.image = UIGraphicsGetImageFromCurrentImageContext(); 
    UIGraphicsEndImageContext();

来源

2015-03-19 05:59:45 Mohanraj

从JSON中将缩略图图像加载到UITableView中

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