使用Base64和JSON上传大图像

Question

我正在使用此功能将图像上传到服务器JSON.为此,我首先将图像转换为NSData然后再NSString使用Base64.当图像不是很大时,该方法可以正常工作,但是当我尝试上传2Mb图像时,它会崩溃.

问题是,即使didReceiveResponse调用该方法以及didReceiveData返回该方法,服务器也不会接收我的图像(null).起初我认为这是一个超时问题,但即使将其设置为1000.0它仍然不起作用.任何的想法？谢谢你的时间!

这是我目前的代码:

 - (void) imageRequest {

   NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:[NSURL URLWithString:@"http://www.myurltouploadimage.com/services/v1/upload.json"]];

   NSString *docDir = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) objectAtIndex:0];
   NSString *path = [NSString stringWithFormat:@"%@/design%i.png",docDir, designNum];
   NSLog(@"%@",path);

   NSData *imageData = UIImagePNGRepresentation([UIImage imageWithContentsOfFile:path]);
   [Base64 initialize];
   NSString *imageString = [Base64 encode:imageData];

   NSArray *keys = [NSArray arrayWithObjects:@"design",nil];
   NSArray *objects = [NSArray arrayWithObjects:imageString,nil];
   NSDictionary *jsonDictionary = [NSDictionary dictionaryWithObjects:objects forKeys:keys];

   NSError *error;
   NSData *jsonData = [NSJSONSerialization dataWithJSONObject:jsonDictionary options:kNilOptions error:&error];

   [request setHTTPMethod:@"POST"];
   [request setValue:[NSString stringWithFormat:@"%d",[jsonData length]] forHTTPHeaderField:@"Content-Length"];
   [request setValue:@"application/json" forHTTPHeaderField:@"Accept"];
   [request setValue:@"application/json" forHTTPHeaderField:@"Content-Type"];
   [request setHTTPBody:jsonData];

   [[NSURLConnection alloc] initWithRequest:request delegate:self];

   NSLog(@"Image uploaded");

}

 - (void) connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response {

   NSLog(@"didReceiveResponse");

}

 - (void) connection:(NSURLConnection *)connection didReceiveData:(NSData *)data {

   NSLog(@"%@",[NSJSONSerialization JSONObjectWithData:data options:kNilOptions error:nil]);

}

Answer 1

我最终决定将Base64图像上传到较小的子串中.为了做到这一点,并且我需要很多NSURLConnections,我创建了一个名为的子类TagConnection,它为每个连接提供了一个标签,这样它们之间就不会产生混淆了.

然后我创建了一个TagConnection属性,MyViewController目的是从任何函数访问它.正如你所看到的,还有的-startAsyncLoad:withTag:是allocs功能和inits的TagConnection和-connection:didReceiveData:它删除它,当我收到服务器的响应之一.

参考该-uploadImage函数,首先,它将图像转换为字符串,然后将其拆分并将块放入JSON请求中.它被调用,直到变量offset大于字符串长度,这意味着已经上传了所有块.

您还可以通过每次检查服务器响应并仅-uploadImage在返回成功时调用该函数来证明每个块已成功上载.

我希望这是一个有用的答案.谢谢.

TagConnection.h

@interface TagConnection : NSURLConnection {
    NSString *tag;
}

@property (strong, nonatomic) NSString *tag;

- (id)initWithRequest:(NSURLRequest *)request delegate:(id)delegate startImmediately:(BOOL)startImmediately tag:(NSString*)tag;

@end

TagConnection.m

#import "TagConnection.h"

@implementation TagConnection

@synthesize tag;

- (id)initWithRequest:(NSURLRequest *)request delegate:(id)delegate startImmediately:(BOOL)startImmediately tag:(NSString*)tag {
    self = [super initWithRequest:request delegate:delegate startImmediately:startImmediately];

    if (self) {
        self.tag = tag;
    }
    return self;
}

- (void)dealloc {
    [tag release];
    [super dealloc];
}

@end

MyViewController.h

#import "TagConnection.h"

@interface MyViewController : UIViewController

@property (strong, nonatomic) TagConnection *conn;

MyViewController.m

#import "MyViewController.h"

@interface MyViewController ()

@end

@synthesize conn;

bool stopSending = NO;
int chunkNum = 1;
int offset = 0;

- (IBAction) uploadImageButton:(id)sender {

    [self uploadImage];

}

- (void) startAsyncLoad:(NSMutableURLRequest *)request withTag:(NSString *)tag {

    self.conn = [[[TagConnection alloc] initWithRequest:request delegate:self startImmediately:YES tag:tag] autorelease];

}

- (void) uploadImage {

    NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:[NSURL URLWithString:@"http://www.mywebpage.com/upload.json"] cachePolicy:NSURLRequestUseProtocolCachePolicy timeoutInterval:1000.0];

    NSString *docDir = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) objectAtIndex:0];
    NSString *path = [NSString stringWithFormat:@"%@/design%i.png", docDir, designNum];
    NSLog(@"%@",path);

    NSData *imageData = UIImagePNGRepresentation([UIImage imageWithContentsOfFile:path]);
    [Base64 initialize];
    NSString *imageString = [Base64 encode:imageData];

    NSUInteger length = [imageString length];
    NSUInteger chunkSize = 1000;

    NSUInteger thisChunkSize = length - offset > chunkSize ? chunkSize : length - offset;
    NSString *chunk = [imageString substringWithRange:NSMakeRange(offset, thisChunkSize)];
    offset += thisChunkSize;

    NSArray *keys = [NSArray arrayWithObjects:@"design",@"design_id",@"fragment_id",nil];
    NSArray *objects = [NSArray arrayWithObjects:chunk,@"design_id",[NSString stringWithFormat:@"%i", chunkNum],nil];
    NSDictionary *jsonDictionary = [NSDictionary dictionaryWithObjects:objects forKeys:keys];

    NSError *error;
    NSData *jsonData = [NSJSONSerialization dataWithJSONObject:jsonDictionary options:kNilOptions error:&error];

    [request setHTTPMethod:@"POST"];
    [request setValue:[NSString stringWithFormat:@"%d",[jsonData length]] forHTTPHeaderField:@"Content-Length"];
    [request setValue:@"application/json" forHTTPHeaderField:@"Accept"];
    [request setValue:@"application/json" forHTTPHeaderField:@"Content-Type"];
    [request setHTTPBody:jsonData];

    [self startAsyncLoad:request withTag:[NSString stringWithFormat:@"tag%i",chunkNum]];

    if (offset > length) {
        stopSending = YES;
    }

}

- (void) connection:(NSURLConnection *)connection didReceiveData:(NSData *)data {

    NSError *error;
    NSArray *responseData = [NSJSONSerialization JSONObjectWithData:data options:kNilOptions error:&error];
    if (!responseData) {
        NSLog(@"Error parsing JSON: %@", error);
    } else {
        if (stopSending == NO) {
            chunkNum++;
            [self.conn cancel];
            self.conn = nil;
            [self uploadImage];
        } else {
            NSLog(@"---------Image sent---------");
        }
    }

}

@end