File download with three examples and runloop doesnt stop

Author: srinikhil-07

HTTPWork.h

@@ -0,0 +1,13 @@
+//
+//  HTTPWork.h
+//  Basics
+//
+//  Created by sri-7348 on 28/08/18.
+//  Copyright © 2018 sri-7348. All rights reserved.
+//
+
+#ifndef HTTPWork_h
+#define HTTPWork_h
+
+
+#endif /* HTTPWork_h */

HTTPWork.m

@@ -0,0 +1,116 @@
+//
+//  HTTPWork.m
+//  Basics
+//
+//  Created by sri-7348 on 28/08/18.
+//  Copyright © 2018 sri-7348. All rights reserved.
+//
+
+#import <Foundation/Foundation.h>
+#import "HTTPWork.h"
+BOOL shouldKeepRunning=YES;
+@implementation HTTPWork
+
+
+-(void) uploadData{
+    NSLog(@"hi");
+}
+
+// needs runloop/async dispatch, make it exit runloop
+// dont use root user!- wont work cos file path changes
+-(void) downloadData{
+    NSString *str=@"https://upload.wikimedia.org/wikipedia/en/6/62/MacOS_Mojave_Desktop.jpg";
+    NSURL *imageURL=[NSURL URLWithString:str];
+    NSMutableURLRequest *dRequest=[NSMutableURLRequest requestWithURL:imageURL];
+    [dRequest setHTTPMethod:@"GET"];
+    NSURLSession *session=[NSURLSession sharedSession];
+    NSURLSessionDownloadTask *download=[session downloadTaskWithRequest:dRequest completionHandler:^(NSURL * _Nullable location, NSURLResponse * _Nullable response, NSError * _Nullable error) {
+        
+            if(error){
+                NSLog(@"Error in download \n");
+                return;
+            }
+            NSFileManager *fileManager = [NSFileManager defaultManager];
+            NSURL *documentsURL = [fileManager URLsForDirectory:NSDocumentDirectory inDomains:NSUserDomainMask][0];
+            NSURL *fileURL = [documentsURL URLByAppendingPathComponent:@"Img1.jpg"];
+            NSError *moveError;
+            if (![fileManager moveItemAtURL:location toURL:fileURL error:&moveError]) {
+                NSLog(@"moveItemAtURL failed: %@", moveError);
+                return;
+            }
+            NSLog(@"Response is %@: \n",response);
+        
+    }];
+    
+    [download resume]; //triggers the download task
+    [[NSRunLoop currentRunLoop]run];
+    NSLog(@"object is: %@ \n",download.progress);
+    }
+
+-(void)saveFilesInLocalDirectory //working but dont use this synchronous methos for network based URL cos takes a lot of time
+{
+    NSString * documentsDirectoryPath = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) objectAtIndex:0];
+    NSString *fileName = @"gandhi.pdf";
+    NSString *fileURL = @"http://www.mkgandhi.org/ebks/mindofmahatmagandhi.pdf";
+    NSFileManager *fileManager = [NSFileManager defaultManager];
+    NSString *writablePath = [documentsDirectoryPath stringByAppendingPathComponent:fileName];
+    if(![fileManager fileExistsAtPath:writablePath]){
+        // file doesn't exist
+        NSLog(@"file doesn't exist");
+        //save Image From URL
+        NSData * data = [NSData dataWithContentsOfURL:[NSURL URLWithString: fileURL]];
+        
+        NSError *error = nil;
+        [data writeToFile:[documentsDirectoryPath stringByAppendingPathComponent:[NSString stringWithFormat:@"%@", fileName]] options:NSAtomicWrite error:&error];
+        
+        if (error) {
+            NSLog(@"Error Writing File : %@",error);
+        }else{
+            NSLog(@"Image %@ Saved SuccessFully",fileName);
+        }
+    }
+    else{
+        // file exist
+        NSLog(@"file exist");
+    }
+}
+
+// this method uses DataTask: use runloop/dispatch_async to make this work!
+// this doesnt exit run loop, TO.DO: make it exit once download over.
+// doesnt work for root user due to file paths
+-(void) saveFilesFast{
+    NSString * documentsDirectoryPath = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) objectAtIndex:0];
+    NSString *str=@"http://upload.wikimedia.org/wikipedia/en/6/62/MacOS_Mojave_Desktop.jpg";
+    NSURL *fileURL=[NSURL URLWithString:str];
+    NSString *fileName = @"image2.jpg";
+    NSFileManager *fileManager = [NSFileManager defaultManager];
+    NSString *writablePath = [documentsDirectoryPath stringByAppendingPathComponent:fileName];
+    NSURLSession *session=[NSURLSession sharedSession];
+    NSURLSessionDataTask *task1=[session dataTaskWithURL:fileURL completionHandler:^(NSData * _Nullable data, NSURLResponse * _Nullable response, NSError * _Nullable error){
+        if(error){ //handle error
+            NSLog(@"Error occured ! \n");
+            NSLog(@"URL response is %@ \n",response);
+            return;
+        }
+        [data writeToFile:[documentsDirectoryPath stringByAppendingPathComponent:[NSString stringWithFormat:@"%@", fileName]] options:NSAtomicWrite error:&error];
+         if(![fileManager fileExistsAtPath:writablePath]){
+             NSLog(@"file doesn't exist");
+             if (error) {
+                 NSLog(@"Error Writing File : %@",error);
+             }
+             
+                NSLog(@"Image %@ Saved SuccessFully",fileName);
+                 shouldKeepRunning=NO;
+            
+         }
+         else{
+             NSLog(@"File exist.\n");
+             shouldKeepRunning=NO;
+         }
+    }];
+    [task1 resume];
+    while(shouldKeepRunning){
+    [[NSRunLoop currentRunLoop]run];
+    }
+}
+@end

main.m

@@ -3,7 +3,7 @@
 #import "DelegatingClass.h"
 #import <SystemConfiguration/SystemConfiguration.h>
 #import <Cocoa/Cocoa.h>
-
+#import "HTTPWork.h"
 
 @interface EgClass: DelegatingClass
 - (void) threadMethod: (int) a;
@@ -220,7 +220,7 @@ int main(int argv, const char* argc[]){
     NSLog(@"Choice 2: Execute command line commands from a process");
     NSLog(@"Choice 3: Execute launchd from this program \n");
     //scanf("%i",&choice);
-    choice=5;
+    choice=7;
     DelegatingClass *boss =[[DelegatingClass alloc]init];
     EgClass *delegatePerson=[[EgClass alloc]init];
     boss.delegate=delegatePerson; //makes egClass conform to Delegate protocol
@@ -291,6 +291,14 @@ int main(int argv, const char* argc[]){
             NSLog(@"Success! \n");
         }
     }
-    
+    else if(choice==7){
+        //http upload and download
+        HTTPWork *httpTask=[[HTTPWork alloc]init];
+        //Download
+        [httpTask downloadData];//SessionDownloadTask example
+        [httpTask saveFilesInLocalDirectory]; //NSData with URL example
+        [httpTask saveFilesFast];// SessionDataTask example
+        NSLog(@"back to main \n");
+    }
     return 0;
 }