【发布时间】：2014-10-25 09:55:36
【问题描述】：
我正在构建一个文章阅读应用程序。我正在从 JSON 链接获取数据，例如 uitableview 中的文章图片和标题。
我无法在 uitableview 中实现分页，假设我的 JSON 链接是 www.example.com&page=1 一次包含 10 篇文章，即 1-10。
当我在像 www.example.com&page=2 这样的 JSON 链接中连接以获得 11-20 篇文章列表时。
我无法实现如何在滚动时在 uitableview 中加载数据并使用数据增加行数。
这是我的代码：
int *x=1;
int *inc=10;
@interface ysTableViewController ()
{
Reachability *internetReachable;
}
@end
@implementation ysTableViewController
- (id)initWithStyle:(UITableViewStyle)style
{
self = [super initWithStyle:style];
if (self) {
// Custom initialization
}
return self;
}
- (void)viewDidLoad
{
[super viewDidLoad];
[self checkInternetConnection];
UILabel *titleLabel = [[UILabel alloc] initWithFrame:CGRectMake(20,10,0,20)];
titleLabel.textColor = [UIColor blackColor];
titleLabel.backgroundColor = [UIColor clearColor];
titleLabel.text = @"Story";
[self.navigationItem setTitleView:titleLabel];
}
- (void)scrollViewDidScroll:(UIScrollView *)aScrollView {
CGPoint offset = aScrollView.contentOffset;
CGRect bounds = aScrollView.bounds;
CGSize size = aScrollView.contentSize;
UIEdgeInsets inset = aScrollView.contentInset;
float y = offset.y + bounds.size.height - inset.bottom;
float h = size.height;
float reload_distance = 10;
if(y > h + reload_distance) {
NSLog(@"load more rows");
inc=inc+10;
BOOL myBool = [self isNetworkAvailable];
if (myBool)
{
@try {
// for table cell seperator line color
self.tableView.separatorColor = [UIColor colorWithRed:190/255.0 green:190/255.0 blue:190/255.0 alpha:1.0];
// for displaying the previous screen lable with back button in details view controller
UIBarButtonItem *backbutton1 = [[UIBarButtonItem alloc] initWithTitle:@"" style:UIBarButtonItemStyleBordered target:nil action:nil];
[[self navigationItem] setBackBarButtonItem:backbutton1];
_Title1 = [[NSMutableArray alloc] init];
_Author1 = [[NSMutableArray alloc] init];
_Images1 = [[NSMutableArray alloc] init];
_Details1 = [[NSMutableArray alloc] init];
_link1 = [[NSMutableArray alloc] init];
_Date1 = [[NSMutableArray alloc] init];
NSString *urlString=[NSString stringWithFormat:@“www.example.com&page=%d",x];
NSLog(@"xxxxx===%d",x);
NSURL *newUrl=[NSURL URLWithString:urlString];
NSData* data = [NSData dataWithContentsOfURL:newUrl];
NSArray *ys_avatars = [NSJSONSerialization JSONObjectWithData:data options:0 error:nil];
x++;
if(ys_avatars){
for (int j=0;j<ys_avatars.count;j++)
{
[_Title1 addObject:ys_avatars[j][@"title"]];
[_Author1 addObject: ys_avatars[j][@"author"]];
[_Images1 addObject: ys_avatars[j][@"featured_img"]];
[_Details1 addObject:ys_avatars[j][@"content"]];
[_link1 addObject:ys_avatars[j][@"permalink"]];
NSString *newStr=[ys_avatars[j][@"date"] substringToIndex:[ys_avatars[j][@"date"] length]-3];
[_Date1 addObject:newStr];
} }
else
{
NSLog(@"asd");
} }
@catch (NSException *exception) {
}
}
}
}
- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView
{
// Return the number of sections.
return 1;
}
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
// Return the number of rows in the section.
return inc;
}
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
static NSString *Cellidentifier1 = @"ysTableViewCell";
ysTableViewCell *cell1 = [tableView dequeueReusableCellWithIdentifier:Cellidentifier1 forIndexPath:indexPath];
// Configure the cell...
long row = [indexPath row];
cell1.TitleLabel1.text = _Title1[row];
cell1.AuthorLabel1.text = _Author1[row];
NSString *yourStoryUrl = [_Images1[indexPath.row] stringByAddingPercentEscapesUsingEncoding:NSASCIIStringEncoding];
if(yourStoryUrl) {
NSArray *subStringsUrl = [yourStoryUrl componentsSeparatedByString:@"/"];
NSString *stripedName = [subStringsUrl lastObject];
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDirectory = [paths objectAtIndex:0];
//Local stored image file path
NSString* filePath =[documentsDirectory stringByAppendingPathComponent:[NSString stringWithFormat:@"%@",stripedName]];
if(filePath) {
UIImage *image = [UIImage imageWithContentsOfFile:filePath];
if(image) {
// Now the image will have been loaded and decoded and is ready to rock for the main thread
ysTableViewCell *updateCell =(id)[tableView cellForRowAtIndexPath:indexPath];
if(updateCell)
updateCell.ThumbImage1.image=image;
cell1.ThumbImage1.image=image;
} else {
dispatch_queue_t taskQ = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);
dispatch_async(taskQ, ^{
NSURL *Imageurl = [NSURL URLWithString:yourStoryUrl];
NSData *data = [NSData dataWithContentsOfURL:Imageurl];
UIImage *images1 = [[UIImage alloc] initWithData:data];
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDirectory = [paths objectAtIndex:0];
NSData *imageData = UIImagePNGRepresentation(images1);
//_imagePath =[documentsDirectory stringByAppendingPathComponent:[NSString stringWithFormat:@"%@.png",stripedName]];
// NSLog((@"pre writing to file"));
if (![imageData writeToFile:filePath atomically:NO])
{
NSLog((@"Failed to cache image data to disk"));
}
else
{
NSLog((@"the cachedImagedPath is %@",filePath));
}
// Now the image will have been loaded and decoded and is ready to rock for the main thread
dispatch_sync(dispatch_get_main_queue(), ^{
ysTableViewCell *updateCell =(id)[tableView cellForRowAtIndexPath:indexPath];
if(updateCell)
updateCell.ThumbImage1.image=images1;
cell1.ThumbImage1.image=images1;
});
});
}
} else {
dispatch_queue_t taskQ = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);
dispatch_async(taskQ, ^{
NSURL *Imageurl = [NSURL URLWithString:yourStoryUrl];
NSData *data = [NSData dataWithContentsOfURL:Imageurl];
UIImage *images1 = [[UIImage alloc] initWithData:data];
// NSString *myString = [Imageurl absoluteString];
// NSLog(@"%@",myString);
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDirectory = [paths objectAtIndex:0];
NSData *imageData = UIImagePNGRepresentation(images1);
_imagePath =[documentsDirectory stringByAppendingPathComponent:[NSString stringWithFormat:@"%@.png",stripedName]];
// NSLog((@"pre writing to file"));
if (![imageData writeToFile:_imagePath atomically:NO])
{
NSLog((@"Failed to cache image data to disk"));
}
else
{
// NSLog((@"the cachedImagedPath is %@",_imagePath));
}
// Now the image will have been loaded and decoded and is ready to rock for the main thread
dispatch_sync(dispatch_get_main_queue(), ^{
ysTableViewCell *updateCell =(id)[tableView cellForRowAtIndexPath:indexPath];
if(updateCell)
updateCell.ThumbImage1.image=images1;
cell1.ThumbImage1.image=images1;
});
});
}
}
return cell1;
}
【问题讨论】：
-
注意 - 您的代码太长了。你绝对必须把它分解成更小的部分。每当您有一段超过 3 行的代码时，请将其设为单独的函数。几乎不可能“阅读”并按原样帮助您的代码 - 希望它有所帮助！
标签： ios objective-c json uitableview pagination