设置下载NSData的进度条 [英] Set progress bar for downloading NSData

问题描述

NSURL *url = [NSURL URLWithString:@"http://i0.kym-cdn.com/entries/icons/original/000/005/545/OpoQQ.jpg?1302279173"]; 
NSData *data = [NSData dataWithContentsOfURL:url]; 
imageView.image = [[[UIImage imageWithData:data];

我想在下载时设置进度条。

I want to set progress bar while downloading.

推荐答案

举一个更详细的例子：

在你的。 h file do

in your .h file do

@interface YourClass : YourSuperclass<NSURLConnectionDataDelegate>

@property (nonatomic) NSMutableData *imageData;
@property (nonatomic) NSUInteger totalBytes;
@property (nonatomic) NSUInteger receivedBytes;

在某个地方打电话

NSURL *url = [NSURL URLWithString:@"http://i0.kym-cdn.com/entries/icons/original/000/005/545/OpoQQ.jpg?1302279173"];
NSURLRequest *request = [NSURLRequest requestWithURL:url];
NSURLConnection *connection = [[NSURLConnection alloc] initWithRequest:request delegate:self startImmediately:YES];

并实施委托方法

- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response
{
    NSHTTPURLResponse *httpResponse = (NSHTTPURLResponse *) urlResponse;
    NSDictionary *dict = httpResponse.allHeaderFields;
    NSString *lengthString = [dict valueForKey:@"Content-Length"];
    NSNumberFormatter *formatter = [[NSNumberFormatter alloc] init];
    NSNumber *length = [formatter numberFromString:lengthString];
    self.totalBytes = length.unsignedIntegerValue;

    self.imageData = [[NSMutableData alloc] initWithCapacity:self.totalBytes];
}

- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data
{
    [self.imageData appendData:data];
    self.receivedBytes += data.length;

    // Actual progress is self.receivedBytes / self.totalBytes
}

- (void)connectionDidFinishLoading:(NSURLConnection *)connection
{
    imageView.image = [UIImage imageWithData:self.imageData];
}

- (void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error
{
    //handle error
}

这篇关于设置下载NSData的进度条的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！