一、首先封装一个下载工具类：
#import <UIKit/UIKit.h>
/** 下载回调信息，下载进度Block
* @param alreadySize 已接收大小
* @param contentLength 文件总大小
*/
typedef void(^ZJDownloaderProgressBlock)(CGFloat alreadySize,CGFloat contentLength);
/**下载回调信息，完成下载Block
* @param data data
* @param error 错误信息
*/
typedef void(^ZJDownloaderCompletedBlock)(NSData *data,NSString *urlStr,NSError *error);
@interface ZJDownloader : NSObject
-(void)downloderWithUrlStr:(NSString *)urlStr ProgressBlock:(ZJDownloaderProgressBlock)progressBlock CompletedBlock:(ZJDownloaderCompletedBlock)completedBlock;
@end
#import "ZJDownloader.h"
@interface ZJDownloader()<NSURLSessionDataDelegate>
@property(strong,nonatomic) NSMutableData * data;
@property(strong,nonatomic) NSString * urlStr;
@property(assign,nonatomic) CGFloat totalSize;
@property (copy, nonatomic) ZJDownloaderProgressBlock progressBlock;
@property (copy, nonatomic) ZJDownloaderCompletedBlock completedBlock;
@end
@implementation ZJDownloader
+(instancetype)share{
static ZJDownloader * downloder;
static dispatch_once_t onceToken;
dispatch_once(&onceToken, ^{
downloder = [[ZJDownloader alloc] init];
});
return downloder;
}
-(void)downloderWithUrlStr:(NSString *)urlStr ProgressBlock:(ZJDownloaderProgressBlock)progressBlock CompletedBlock:(ZJDownloaderCompletedBlock)completedBlock{
[self setProgressBlock:progressBlock];
[self setCompletedBlock:completedBlock];
[self setUrlStr:urlStr];
[self startDowloderWithUrlStr:urlStr];
//NSLog(@" === 开始下载 === %@",urlStr);
}
#pragma mark -
-(void)startDowloderWithUrlStr:(NSString *)urlStr{
NSURLSessionConfiguration *configura = [NSURLSessionConfiguration defaultSessionConfiguration];
NSURLSession *session = [NSURLSession sessionWithConfiguration:configura delegate:self delegateQueue:nil];
NSURL * url = [NSURL URLWithString:urlStr];
NSMutableURLRequest *request = [[NSMutableURLRequest alloc] initWithURL:url cachePolicy: NSURLRequestReloadIgnoringLocalCacheData timeoutInterval:MAXFLOAT];
NSURLSessionDataTask *dataTask = [session dataTaskWithRequest:request];
[dataTask resume];
[session finishTasksAndInvalidate];
}
#pragma mark - NSURLSessionDataDelegate
//最先调用，在这里做一些数据的初始化。
-(void)URLSession:(NSURLSession *)session dataTask:(NSURLSessionDataTask *)dataTask didReceiveResponse:(NSURLResponse *)response completionHandler:(void (^)(NSURLSessionResponseDisposition))completionHandler{
self.data = [[NSMutableData alloc] init];
// 文件总大小
long totalLength = response.expectedContentLength;
[self setTotalSize:totalLength];
completionHandler(NSURLSessionResponseAllow);
}
//下载响应
- (void)URLSession:(NSURLSession *)session dataTask:(NSURLSessionDataTask *)dataTask
didReceiveData:(NSData *)data{
[self.data appendData:data];
// 已经下载的大小
long length = self.data.length;
if(self.progressBlock){
self.progressBlock(length,self.totalSize);
}
}
//下载完成后调用
-(void)URLSession:(NSURLSession *)session task:(NSURLSessionTask *)task didCompleteWithError:(NSError *)error{
if (!error) {
if(self.completedBlock){
self.completedBlock(self.data, self.urlStr, nil);
}
}else{
if(self.completedBlock){
self.completedBlock(nil,self.urlStr, error);
}
}
}
@end
二、对下载工具类二次封装：
#import <Foundation/Foundation.h>
#import "ZJDownloader.h"
@interface ZJDownloaderManager : NSObject
+(instancetype)share;
-(void)downloderWithUrlStr:(NSString *)urlStr ProgressBlock:(ZJDownloaderProgressBlock)progressBlock CompletedBlock:(ZJDownloaderCompletedBlock)completedBlock;
@end
#import "ZJDownloaderManager.h"
@interface ZJDownloaderManager()
@property(strong,nonatomic) dispatch_queue_t concurrentQueue;// GCD队列
@property(nonatomic,strong) NSMutableDictionary * operations;//
@end
static ZJDownloaderManager * manager = nil;
@implementation ZJDownloaderManager
+(instancetype)share{
static dispatch_once_t onceToken;
dispatch_once(&onceToken, ^{
manager = [[self alloc] init];
});
return manager;
}
-(dispatch_queue_t)concurrentQueue{
if(_concurrentQueue==nil){
/** 创建唯一表示为“downloderImageQueue”的并发队列
* DISPATCH_QUEUE_CONCURRENT 指定并发队列
*/
_concurrentQueue = dispatch_queue_create("ZJDownloderQueue", DISPATCH_QUEUE_CONCURRENT);
}
return _concurrentQueue;
}
-(NSMutableDictionary *)operations{
if(_operations==nil){
_operations = [NSMutableDictionary dictionary];
}
return _operations;
}
-(void)downloderWithUrlStr:(NSString *)urlStr ProgressBlock:(ZJDownloaderProgressBlock)progressBlock CompletedBlock:(ZJDownloaderCompletedBlock)completedBlock{
[self methodOneloderWithUrlStr:urlStr
ProgressBlock:progressBlock
CompletedBlock:completedBlock];
}
/** 同步并行
*/
-(void)methodThreeloderWithUrlStr:(NSString *)urlStr ProgressBlock:(ZJDownloaderProgressBlock)progressBlock CompletedBlock:(ZJDownloaderCompletedBlock)completedBlock{
if([self.operations objectForKey:urlStr]){ return;}
__weak typeof(self) weakSelf = self;
dispatch_sync([self concurrentQueue], ^{ // 同步并行
ZJDownloader * downloader = [ZJDownloader new];
[downloader downloderWithUrlStr:urlStr ProgressBlock:^(CGFloat alreadySize, CGFloat contentLength) {
dispatch_sync(dispatch_get_main_queue(), ^{
progressBlock(alreadySize,contentLength);
});
} CompletedBlock:^(NSData *data, NSString *urlStr, NSError *error) {
dispatch_sync(dispatch_get_main_queue(), ^{
completedBlock(data, urlStr, error);
[weakSelf.operations removeObjectForKey:urlStr];
});
}];
[weakSelf.operations setObject:downloader forKey:urlStr];
});
}
/** 同步 dispatch_barrier_sync
*/
-(void)methodFourloderWithUrlStr:(NSString *)urlStr ProgressBlock:(ZJDownloaderProgressBlock)progressBlock CompletedBlock:(ZJDownloaderCompletedBlock)completedBlock{
if([self.operations objectForKey:urlStr]){ return;}
__weak typeof(self) weakSelf = self;
dispatch_barrier_sync([self concurrentQueue], ^{
ZJDownloader * downloader = [ZJDownloader new];
[downloader downloderWithUrlStr:urlStr ProgressBlock:^(CGFloat alreadySize, CGFloat contentLength) {
dispatch_async([self concurrentQueue], ^{
dispatch_sync(dispatch_get_main_queue(), ^{
progressBlock(alreadySize,contentLength);
});
});
} CompletedBlock:^(NSData *data, NSString *urlStr, NSError *error) {
dispatch_sync([self concurrentQueue], ^{
dispatch_sync(dispatch_get_main_queue(), ^{
completedBlock(data, urlStr, error);
[weakSelf.operations removeObjectForKey:urlStr];
});
});
}];
[weakSelf.operations setObject:downloader forKey:urlStr];
});
}