NSURL 提取参数字符串中某个键的单个值

Question

我有一个 NSURL:

serverCall?x=a&y=b&z=c

获取 y 值的最快、最有效的方法是什么？

谢谢

Answer 1

更新：

自 2010 年撰写本文以来，Apple 似乎已经为此目的发布了一套工具。请参阅下面的答案。

老派解决方案：

嗯，我知道你说“最快的方法”，但在我开始使用 NSScanner 进行测试后，我就是做不到停止。虽然这不是最短的方法，但如果您打算经常使用该功能，那么它肯定很方便。我创建了一个 URLParser 类，它使用 NSScanner 获取这些变量。使用很简单：

URLParser *parser = [[[URLParser alloc] initWithURLString:@"http://blahblahblah.com/serverCall?x=a&y=b&z=c&flash=yes"] autorelease];
NSString *y = [parser valueForVariable:@"y"];
NSLog(@"%@", y); //b
NSString *a = [parser valueForVariable:@"a"];
NSLog(@"%@", a); //(null)
NSString *flash = [parser valueForVariable:@"flash"];
NSLog(@"%@", flash); //yes

执行此操作的类如下（*源文件位于帖子底部）：

URLParser.h

@interface URLParser : NSObject {
    NSArray *variables;
}

@property (nonatomic, retain) NSArray *variables;

- (id)initWithURLString:(NSString *)url;
- (NSString *)valueForVariable:(NSString *)varName;

@end

URLParser.m

@implementation URLParser
@synthesize variables;

- (id) initWithURLString:(NSString *)url{
    self = [super init];
    if (self != nil) {
        NSString *string = url;
        NSScanner *scanner = [NSScanner scannerWithString:string];
        [scanner setCharactersToBeSkipped:[NSCharacterSet characterSetWithCharactersInString:@"&?"]];
        NSString *tempString;
        NSMutableArray *vars = [NSMutableArray new];
        [scanner scanUpToString:@"?" intoString:nil];       //ignore the beginning of the string and skip to the vars
        while ([scanner scanUpToString:@"&" intoString:&tempString]) {
            [vars addObject:[tempString copy]];
        }
        self.variables = vars;
        [vars release];
    }
    return self;
}

- (NSString *)valueForVariable:(NSString *)varName {
    for (NSString *var in self.variables) {
        if ([var length] > [varName length]+1 && [[var substringWithRange:NSMakeRange(0, [varName length]+1)] isEqualToString:[varName stringByAppendingString:@"="]]) {
            NSString *varValue = [var substringFromIndex:[varName length]+1];
            return varValue;
        }
    }
    return nil;
}

- (void) dealloc{
    self.variables = nil;
    [super dealloc];
}

@end

*if你不喜欢复制和粘贴，你可以下载源文件 - 我写了一篇关于这个的快速博客文章 此处。

Answer 2

这里有很多自定义 url 解析器，记住 NSURLComponents 是你的朋友！

提取了 url 编码参数

这是一个示例，我为“page” Swift

let myURL = "www.something.com?page=2"

var pageNumber : Int?
if let queryItems = NSURLComponents(string: myURL)?.queryItems {
    for item in queryItems {
        if item.name == "page" {
           if let itemValue = item.value {
               pageNumber = Int(itemValue)
           }
        }
    }
}
print("Found page number: \(pageNumber)")

Objective-C

NSString *myURL = @"www.something.com?page=2";
NSURLComponents *components = [NSURLComponents componentsWithString:myURL];
NSNumber *page = nil;
for(NSURLQueryItem *item in components.queryItems)
{
    if([item.name isEqualToString:@"page"])
        page = [NSNumber numberWithInteger:item.value.integerValue];
}

“为什么要重新发明轮子！” - 聪明人

Answer 3

我很确定你必须自己解析它。不过，情况还不错：

NSString * q = [myURL query];
NSArray * pairs = [q componentsSeparatedByString:@"&"];
NSMutableDictionary * kvPairs = [NSMutableDictionary dictionary];
for (NSString * pair in pairs) {
  NSArray * bits = [pair componentsSeparatedByString:@"="];
  NSString * key = [[bits objectAtIndex:0] stringByReplacingPercentEscapesUsingEncoding:NSUTF8StringEncoding];
  NSString * value = [[bits objectAtIndex:1] stringByReplacingPercentEscapesUsingEncoding:NSUTF8StringEncoding];
  [kvPairs setObject:value forKey:key];
}

NSLog(@"y = %@", [kvPairs objectForKey:@"y"]);

Answer 4

在 Swift 中，您可以使用 NSURLComponents 将 NSURL 的查询字符串解析为 [AnyObject]。

然后，您可以从中创建一个字典（或直接访问项目）以获取键/值对。作为一个例子，我用它来解析 NSURL 变量 url：

let urlComponents = NSURLComponents(URL: url, resolvingAgainstBaseURL: false)
let items = urlComponents?.queryItems as [NSURLQueryItem]
var dict = NSMutableDictionary()
for item in items{
    dict.setValue(item.value, forKey: item.name)
}
println(dict["x"])

Answer 5

我一直在使用此类别：https://github.com/carlj/NSURL-Parameters。

它体积小且易于使用：

#import "NSURL+Parameters.h"
...
NSURL *url = [NSURL URLWithString:@"http://foo.bar.com?paramA=valueA¶mB=valueB"];
NSString *paramA = url[@"paramA"];
NSString *paramB = url[@"paramB"];

Answer 6

您可以使用 Mac 版 Google 工具箱。
它向 NSString 添加了一个函数，用于将查询字符串转换为字典。

http://code.google.com/p/google-toolbox-for- mac/

它就像一个魅力

        NSDictionary * d = [NSDictionary gtm_dictionaryWithHttpArgumentsString:[[request URL] query]];

Answer 7

下面是一个 Swift 2.0 扩展，它提供了对参数的简单访问：

extension NSURL {
    var params: [String: String] {
        get {
            let urlComponents = NSURLComponents(URL: self, resolvingAgainstBaseURL: false)
            var items = [String: String]()
            for item in urlComponents?.queryItems ?? [] {
                items[item.name] = item.value ?? ""
            }
            return items
        }
    }
} 

示例用法：

let url = NSURL(string: "http://google.com?test=dolphins")
if let testParam = url.params["test"] {
    print("testParam: \(testParam)")
}

Answer 8

我编写了一个简单的类别来扩展 NSString/NSURL，它允许您单独提取 URL 查询参数或作为键/值对的字典：

https://github.com/nicklockwood/RequestUtils

Answer 9

我使用基于 @Dimitris 解决方案的类别方法来做到这一点

#import "NSURL+DictionaryValue.h"

@implementation NSURL (DictionaryValue)
-(NSDictionary *)dictionaryValue
{
NSString *string =  [[self.absoluteString stringByReplacingOccurrencesOfString:@"+" withString:@" "]
                     stringByReplacingPercentEscapesUsingEncoding:NSUTF8StringEncoding];
NSScanner *scanner = [NSScanner scannerWithString:string];
[scanner setCharactersToBeSkipped:[NSCharacterSet characterSetWithCharactersInString:@"&?"]];

NSString *temp;
NSMutableDictionary *dict = [[[NSMutableDictionary alloc] init] autorelease];
[scanner scanUpToString:@"?" intoString:nil];       //ignore the beginning of the string and skip to the vars
while ([scanner scanUpToString:@"&" intoString:&temp]) 
{
    NSArray *parts = [temp componentsSeparatedByString:@"="];
    if([parts count] == 2)
    {
        [dict setObject:[parts objectAtIndex:1] forKey:[parts objectAtIndex:0]];
    }
}

return dict;
}
@end

Answer 10

当前的所有答案都是特定于版本的或不必要的浪费。如果您只想要一个值，为什么要创建字典呢？

这是一个支持所有 iOS 版本的简单答案：

- (NSString *)getQueryParam:(NSString *)name  fromURL:(NSURL *)url
{
    if (url)
    {
        NSArray *urlComponents = [url.query componentsSeparatedByString:@"&"];
        for (NSString *keyValuePair in urlComponents)
        {
            NSArray *pairComponents = [keyValuePair componentsSeparatedByString:@"="];
            NSString *key = [[pairComponents firstObject] stringByRemovingPercentEncoding];

            if ([key isEqualToString:name])
            {
                return [[pairComponents lastObject] stringByRemovingPercentEncoding];
            }
        }
    }
    return nil;
}

Answer 11

你可以简单地做到这一点：

- (NSMutableDictionary *) getUrlParameters:(NSURL *) url
{
    NSMutableDictionary *params = [[NSMutableDictionary alloc] init];
    NSString *tmpKey = [url query];
    for (NSString *param in [[url query] componentsSeparatedByString:@"="])
    {
        if ([tmpKey rangeOfString:param].location == NSNotFound)
        {
            [params setValue:param forKey:tmpKey];
            tmpKey = nil;
        }
        tmpKey = param;
    }
    [tmpKey release];

    return params;
}

它返回像这样的字典：Key = value

Answer 12

我稍微编辑了 Dimitris 的代码，以实现更好的内存管理和效率。此外，它也适用于 ARC。

URLParser.h

@interface URLParser : NSObject

- (void)setURLString:(NSString *)url;
- (NSString *)valueForVariable:(NSString *)varName;

@end

URLParser.m

#import "URLParser.h"

@implementation URLParser {
    NSMutableDictionary *_variablesDict;
}

- (void)setURLString:(NSString *)url {
    [_variablesDict removeAllObjects];

    NSString *string = url;
    NSScanner *scanner = [NSScanner scannerWithString:string];
    [scanner setCharactersToBeSkipped:[NSCharacterSet characterSetWithCharactersInString:@"&?"]];
    NSString *tempString;

    [scanner scanUpToString:@"?" intoString:nil];       //ignore the beginning of the string and skip to the vars
    while ([scanner scanUpToString:@"&" intoString:&tempString]) {
        NSString *dataString = [tempString copy];
        NSArray *sepStrings = [dataString componentsSeparatedByString:@"="];
        if ([sepStrings count] == 2) {
            [_variablesDict setValue:sepStrings[1] forKeyPath:sepStrings[0]];
        }
    }
}

- (id)init
{
    self = [super init];
    if (self) {
        _variablesDict = [[NSMutableDictionary alloc] init];
    }
    return self;
}

- (NSString *)valueForVariable:(NSString *)varName {
    NSString *val = [_variablesDict valueForKeyPath:varName];
    return val;
    return nil;
}

-(NSString *)description {
    return [NSString stringWithFormat:@"Current Variables: %@", _variablesDict];
}

@end

Answer 13

最快的是：

NSString* x = [url valueForQueryParameterKey:@"x"];