使用带有NSString stringWithFormat的url字符串的最佳实践是什么

Question

我使用NSString stringWithFormat方法创建一个URL字符串.但是现在我有一个"快速"编辑这个字符串的问题.

例如,我在服务器上有一个脚本,用于处理带参数的请求.

我有一个像这样的URL字符串:

http://www.domain.com/api/?param1=%@&param2=%@&param3=%@&param4=%@&param5=%@&

但是当我有超过5个,6个参数时,很难修改这个字符串.

任何人都知道如何创建URL字符串的最佳方法(我的意思是当我们修改它时).

Answer 1

这是一个如何以安全的方式添加参数的示例.长但可靠.

NSString* const kBaseURL = @"http://maps.google.com/maps/api/geocode/xml";
NSMutableDictionary *parameterDic = [NSMutableDictionary dictionary];
[parameterDic setObject:@"plaza de la puerta del sol 1, madrid, spain" forKey:@"address"];
[parameterDic setObject:@"false" forKey:@"sensor"];

NSMutableArray *parameters = [NSMutableArray array];
for (__strong NSString *name in parameterDic) {
    NSString *value = [parameterDic objectForKey:name];
    name = encodeToPercentEscapeString(name);
    value = encodeToPercentEscapeString(value);
    NSString *queryComponent = [NSString stringWithFormat:@"%@=%@", name, value];
    [parameters addObject:queryComponent];
}
NSString *query = [parameters componentsJoinedByString:@"&"];
NSString *urlString = [NSString stringWithFormat:@"%@?%@", kBaseURL, query];
NSURL *url = [NSURL URLWithString:urlString];
NSLog(@"%@",url);

上面的代码调用此C函数,因为stringByAddingPercentEscapesUsingEncoding不会转换参数名称或值中的某些特殊字符.正如Jesse Rusak所指出的,在iOS中查看适当的URL(百分比)编码以进行讨论.

// remove CFBridgingRelease and __bridge if your code is not ARC
NSString* encodeToPercentEscapeString(NSString *string) {
    return (NSString *)
        CFBridgingRelease(CFURLCreateStringByAddingPercentEscapes(NULL,
                                            (__bridge CFStringRef) string,
                                            NULL,
                                            (CFStringRef) @"!*'();:@&=+$,/?%#[]",
                                            kCFStringEncodingUTF8));
}

这打印

http://maps.google.com/maps/api/geocode/xml?sensor=false&address=plaza%20de%20la%20puerta%20del%20sol%201,%20madrid,%20spain

奖金跟踪:如何解构和重建字符串:

NSString *stringUrl = @"http://www.google.com:80/a/b/c;params?m=n&o=p#fragment";
NSURL *url = [NSURL URLWithString:stringUrl];
NSLog(@"%@",stringUrl);
NSLog(@"         scheme: %@",[url scheme]);
NSLog(@"           host: %@",[url host]);
NSLog(@"           port: %@",[url port]);
NSLog(@"           path: %@",[url path]);
NSLog(@"   relativePath: %@",[url relativePath]);
NSLog(@"parameterString: %@",[url parameterString]);
NSLog(@"          query: %@",[url query]);
NSLog(@"       fragment: %@",[url fragment]);

NSMutableString *s = [NSMutableString string];
[s appendFormat:@"%@://%@",[url scheme],[url host]];
if ([url port]!=nil){
    [s appendFormat:@":%@",[url port]];
}
[s appendFormat:@"%@",[url path]];
if ([url parameterString]!=nil){
    [s appendFormat:@";%@",[url parameterString]];
}
if ([url query]!=nil){
    [s appendFormat:@"?%@",[url query]];
}
if ([url fragment]!=nil){
    [s appendFormat:@"#%@",[url fragment]];
}
NSLog(@"%@",s);

这打印

http://www.google.com:80/a/b/c;params?m=n&o=p#fragment
         scheme: http
           host: www.google.com
           port: 80
           path: /a/b/c
   relativePath: /a/b/c
parameterString: params
          query: m=n&o=p
       fragment: fragment