CODEWITHSUNDEEP
objective-cnsurlconnectionnsdata
erik
erik

Reputation: 4958

checking for bad NSURLConnection

i am new to Objective-C and going through the book, The Big Nerd Ranch Guide to Objective-C programming.. 

#import <Foundation/Foundation.h>

int main(int argc, const char * argv[])
{

    @autoreleasepool {

        NSURL *url = [NSURL URLWithString:@"http://www.google.com/imagess/logos/ps_logo2.png"];

        NSURLRequest *request = [NSURLRequest requestWithURL:url];

        NSError *error =nil;

        NSData *data = [NSURLConnection sendSynchronousRequest:request
                                             returningResponse:NULL
                                                         error:&error];



        if(!data){
            NSLog(@"fetch failed %@", [error localizedDescription]);
            return 1;
        }

        NSLog(@"the files is %lu bytes", [data length]);

        BOOL written = [data writeToFile:@"/tmp/google.png"
                                 options:NSDataWritingAtomic
                                   error:&error];

        if(!written){
            NSLog(@"write failed: %@",[error localizedDescription]);
            return 1;
        }
        NSLog(@"Success!");

        NSData *readData = [NSData dataWithContentsOfFile:@"/tmp/google.png"];
        NSLog(@"the file read from disk has %lu bytes", [readData length]);

    }
    return 0;
}

the problem is this, if i change the *url to http://aFakeDomain.com/imimimi/myImage.png then my data object will be nill because there is no HOST and everything works fine.. but if i use google as the domain and point to a bad file location then the data object stil has header info and is NOT nil thus i never get the error i should.

whats the best way to make sure that the *url successfully found a file.

thanks

Upvotes: 1

Views: 453

Answers (3)

yebw
yebw

Reputation: 247

There are also some mistakes of the file name; instead of @"/tmp/google.png", you should use the code list blow:

NSArray *paths = NSSearchPathForDirectoriesInDomains(NSLibraryDirectory, NSUserDomainMask, YES);
NSString *filePath = [[paths objectAtIndex:0] stringByAppendingPathComponent:@"google.png"];

Upvotes: 0

KDaker
KDaker

Reputation: 5909

You will need to pass a response to the NSURLConnection call and then check its status code:

NSHTTPURLResponse* httpResponse = (NSHTTPURLResponse*)response;
NSData *data = [NSURLConnection sendSynchronousRequest:request
                                         returningResponse:&httpResponse
                                                     error:&error];
int code = [httpResponse statusCode];

you will get a 404 status code in your case.

Upvotes: 3

user1740901
user1740901

Reputation: 

NSUrlResponce *responce = nil;
NSData *data = [NSURLConnection sendSynchronousRequest:request
                                         returningResponse:&responce
                                                     error:&error];

if (error) {
    // handle the error
}

if (![[responce MIMEType] isEqualToString:@"image/png"]) {
    // failed to get png file
}

Upvotes: 2

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