Add fields to NSMutableURLRequest

Question

How would I add key value pairs to the body of a NSMutableURLRequest? I know I could use something like this:

NSURL *url = [[NSURL alloc] initWithString:@"http://localhost:8080/upload/"];
NSMutableURLRequest *request = [[NSMutableURLRequest alloc] initWithURL:url];
[request setHTTPMethod:@"POST"];
NSString *bodyContents = @"fileName=";
[bodyContents stringByAppendingString:fileName];
[bodyContents stringByAppendingString:@"&"];
[bodyContents stringByAppendingString:@"deviceName="];
[bodyContents stringByAppendingString:deviceName];
[bodyContents stringByAppendingString:@"fileContents="];
[bodyContents stringByAppendingString:fileContents];

But that seems like a lot of hassle, especially if I get to where I need to submit a lot of values in a request. I would hope apple would provide a method like [request addBodyField:@"fileName":fileName] or something equally useful, but I haven't been able to find one in the documentation. Is there one I'm missing or should I just stick to appending strings?

Answer 1

Lots of good answers here. Here's what I do: I built a parameter class that takes care of the pairing syntax as well as url encoding.

#import "NSString+URLEncoding.h"

@interface UrlParameter ()

@property (strong, nonatomic) NSString *pair;
@property (strong, nonatomic) NSString *encodedPair;

@end

@implementation UrlParameter

@synthesize pair = _pair;
@synthesize encodedPair = _encodedPair;


+ (UrlParameter *)withName:(NSString *)name value:(NSString *)value {

    UrlParameter *answer = [[UrlParameter alloc] init];
    answer.pair = [NSString stringWithFormat:@"%@=%@", name, value];
    answer.encodedPair = [NSString stringWithFormat:@"%@=%@", [name urlEncode], [value urlEncode]];

    return answer;  // autorelease if non-ARC
}

@end

This relies on this NSString category method that I cobbled out of a couple posts. (Also ARC-ready):

@implementation NSString (URLEncoding)

- (NSString *)urlEncodeUsingEncoding:(CFStringEncoding)encoding {

    return CFBridgingRelease(CFURLCreateStringByAddingPercentEscapes(kCFAllocatorDefault,
                                                               (__bridge CFStringRef)self,
                                                               NULL,
                                                               CFSTR("!*'();:@&=+$,/?%#[]"),
                                                               encoding));
}

- (NSString *)urlEncode {
    return [self urlEncodeUsingEncoding:kCFStringEncodingUTF8];
}

@end

I also subclass the URL request and give it mutable array of parameters, then, before it starts, it does this:

// in the interface
@property (strong, nonatomic) NSMutableArray *parameters;

- (void)prepareParameters {

    NSMutableString *encodedParameterPairs = [NSMutableString stringWithCapacity:256];

    int position = 1;
    for (UrlParameter *requestParameter in self.parameters) {
        [encodedParameterPairs appendString:[requestParameter encodedPair]];
        if (position < [self.parameters count]) [encodedParameterPairs appendString:@"&"];
        position++;
    }

    if ([[self HTTPMethod] isEqualToString:@"GET"] || [[self HTTPMethod] isEqualToString:@"DELETE"]) {

        NSString *urlString = [NSString stringWithFormat:@"%@?%@", [self URLString], encodedParameterPairs];
        [self setURL:[NSURL URLWithString:urlString]];

    } else {

        // POST, PUT
        NSData *postData = [encodedParameterPairs dataUsingEncoding:NSASCIIStringEncoding allowLossyConversion:YES];
        [self setHTTPBody:postData];
        [self setValue:[NSString stringWithFormat:@"%d", [postData length]] forHTTPHeaderField:@"Content-Length"];
        [self setValue:@"application/x-www-form-urlencoded" forHTTPHeaderField:@"Content-Type"];
    }
}