使用NSMutableURLRequest请求网络
NSString *range = [NSString stringWithFormat:@"bytes=%zd-", self.currentLength];
[request setValue:range forHTTPHeaderField:@"Range"];
[[NSFileManager defaultManager] createFileAtPath:self.filePath contents:nil attributes:nil];
NSFileHandle *handle = [NSFileHandle fileHandleForWritingAtPath:self.filePath];
#import "ViewController.h"
@interface ViewController ()<NSURLConnectionDataDelegate>
@property (weak, nonatomic) IBOutlet UISlider *slider;
@property(nonatomic, assign)NSInteger countLength;
@property(nonatomic, assign)NSInteger currentLength;
@property(nonatomic, strong)NSString *filePath;
@property(nonatomic, strong)NSFileHandle *handle;
@property(nonatomic, strong)NSURLConnection *connec;
@end
@implementation ViewController
- (IBAction)start {
[self downloadStart];
}
- (IBAction)pause {
NSLog(@"%s", __func__);
[self.connec cancel];
}
- (IBAction)resume {
[self downloadStart];
}
- (void)downloadStart{
NSLog(@"%s", __func__);
NSURL *url = [NSURL URLWithString:@"http://desk.fd.zol-img.com.cn/t_s1920x1080c5/g5/M00/04/0E/ChMkJ1xG8LOISDE0AENk28OsmWwAAuhiwDQMkoAQ2Tz651.jpg?downfile=1551085025259.jpg"];
NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:url];
NSString *range = [NSString stringWithFormat:@"bytes=%zd-", self.currentLength];
[request setValue:range forHTTPHeaderField:@"Range"];
self.connec = [[NSURLConnection alloc] initWithRequest:request delegate:self];
}
- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response{
NSLog(@"%s", __func__);
if(self.countLength > 0){
return;
}
self.countLength = response.expectedContentLength;
self.filePath = [[NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES)lastObject] stringByAppendingPathComponent:@"fengjing.jpg"];
[[NSFileManager defaultManager] createFileAtPath:self.filePath contents:nil attributes:nil];
NSFileHandle *handle = [NSFileHandle fileHandleForWritingAtPath:self.filePath];
self.handle = handle;
}
- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data{
[self.handle seekToEndOfFile];
[self.handle writeData:data];
self.currentLength += data.length;
CGFloat progress = 1.0 * self.currentLength / self.countLength;
NSLog(@"当前下载进度:%.2f", progress);
self.slider.value = progress;
}
- (void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error{
[self destroyHandle];
NSLog(@"%s", __func__);
}
- (void)connectionDidFinishLoading:(NSURLConnection *)connection{
[self destroyHandle];
NSLog(@"%s", __func__);
NSLog(@"%@", self.filePath);
}
- (void)destroyHandle{
[self.handle closeFile];
self.handle = nil;
}
@end
