http://example.com?param1=value1&param2=param2

直接使用字符串分割

// Swift代码，IOS8以上

extension String {

    /// 从String中截取出参数
    var urlParameters: [String: AnyObject]? {
        // 判断是否有参数
        guard let start = self.rangeOfString("?") else {
            return nil
        }

        var params = [String: AnyObject]()
        // 截取参数
        let index = start.startIndex.advancedBy(1)
        let paramsString = substringFromIndex(index)

        // 判断参数是单个参数还是多个参数
        if paramsString.containsString("&") {

            // 多个参数，分割参数
            let urlComponents = paramsString.componentsSeparatedByString("&")

            // 遍历参数
            for keyValuePair in urlComponents {
                // 生成Key/Value
                let pairComponents = keyValuePair.componentsSeparatedByString("=")
                let key = pairComponents.first?.stringByRemovingPercentEncoding
                let value = pairComponents.last?.stringByRemovingPercentEncoding
                // 判断参数是否是数组
                if let key = key, value = value {
                    // 已存在的值，生成数组
                    if let existValue = params[key] {
                        if var existValue = existValue as? [AnyObject] {

                            existValue.append(value)
                        } else {
                            params[key] = [existValue, value]
                        }

                    } else {

                        params[key] = value
                    }

                }
            }

        } else {

            // 单个参数
            let pairComponents = paramsString.componentsSeparatedByString("=")

            // 判断是否有值
            if pairComponents.count == 1 {
                return nil
            }

            let key = pairComponents.first?.stringByRemovingPercentEncoding
            let value = pairComponents.last?.stringByRemovingPercentEncoding
            if let key = key, value = value {
                params[key] = value
            }

        }


        return params
    }
}

// Objective-C IOS8以上

@implementation NSString (Utils)

/**
 *  截取URL中的参数
 *
 *  @return NSMutableDictionary parameters
 */
- (NSMutableDictionary *)getURLParameters {

    // 查找参数
    NSRange range = [self rangeOfString:@"?"];
    if (range.location == NSNotFound) {
        return nil;
    }

    NSMutableDictionary *params = [NSMutableDictionary dictionary];

    // 截取参数
    NSString *parametersString = [self substringFromIndex:range.location + 1];

    // 判断参数是单个参数还是多个参数
    if ([parametersString containsString:@"&"]) {

        // 多个参数，分割参数
        NSArray *urlComponents = [parametersString componentsSeparatedByString:@"&"];

        for (NSString *keyValuePair in urlComponents) {
            // 生成Key/Value
            NSArray *pairComponents = [keyValuePair componentsSeparatedByString:@"="];
            NSString *key = [pairComponents.firstObject stringByRemovingPercentEncoding];
            NSString *value = [pairComponents.lastObject stringByRemovingPercentEncoding];

            // Key不能为nil
            if (key == nil || value == nil) {
                continue;
            }

            id existValue = [params valueForKey:key];

            if (existValue != nil) {

                // 已存在的值，生成数组
                if ([existValue isKindOfClass:[NSArray class]]) {
                    // 已存在的值生成数组
                    NSMutableArray *items = [NSMutableArray arrayWithArray:existValue];
                    [items addObject:value];

                    [params setValue:items forKey:key];
                } else {

                    // 非数组
                    [params setValue:@[existValue, value] forKey:key];
                }

            } else {

                // 设置值
                [params setValue:value forKey:key];
            }
        }
    } else {
        // 单个参数

        // 生成Key/Value
        NSArray *pairComponents = [parametersString componentsSeparatedByString:@"="];

        // 只有一个参数，没有值
        if (pairComponents.count == 1) {
            return nil;
        }

        // 分隔值
        NSString *key = [pairComponents.firstObject stringByRemovingPercentEncoding];
        NSString *value = [pairComponents.lastObject stringByRemovingPercentEncoding];

        // Key不能为nil
        if (key == nil || value == nil) {
            return nil;
        }

        // 设置值
        [params setValue:value forKey:key];
    }

    return params;
}

@end

使用案例：

// Swift

let url = "http://example.com?param1=value1&param2=value2"
let url1 = "http://example.com?param1=value1&param1=value2"
let params = url.urlParameters
let params1 = url1.urlParameters
// 字典
print(params)
// 数组
print(params1)

/// 结果
Optional([“param1”: value1, “param2”: value2]) 
Optional([“param1”: ( value1, value2 ) ])

Objective-C

NSString *url = @"http://example.com?param1=value1&param2=value2";
NSString *url1 = @"http://example.com?param1=value1&param1=value2";
NSDictionary *dic = [url getURLParameters];
NSDictionary *dic1 = [url1 getURLParameters];
NSLog(@"dic ---- \n%@", dic);
NSLog(@"dic1 ---- \n%@", dic1);

/// 结果
2016-08-18 14:14:05.943 test[8591:784432] dic ---- 
{
    param1 = value1;
    param2 = value2;
}

2016-08-18 14:15:05.210 test[8625:788127] dic1 ---- 
{
    param1 =     (
        value1,
        value2
    );
}

另一种方法则是使用系统的类 NSURLComponents

// Swift
let url = "http://example.com?param1=value1&param2=value2"
let urlComponents = NSURLComponents(string: url)
let queryItems = urlComponents?.queryItems
for item in queryItems! {
    print(item.name)
    print(item.value)

}

以下方法和上面的截取方法一样，会更简洁：

extension String {
    /// 从String中截取出参数
    var urlParameters: [String: AnyObject]? {
        // 截取是否有参数
        guard let urlComponents = NSURLComponents(string: self), let queryItems = urlComponents.queryItems else {
            return nil
        }
        // 参数字典
        var parameters = [String: AnyObject]()
        
        // 遍历参数
        queryItems.forEach({ (item) in
            
            // 判断参数是否是数组
            if let existValue = parameters[item.name], let value = item.value {
                // 已存在的值，生成数组
                if var existValue = existValue as? [AnyObject] {
                    
                    existValue.append(value as AnyObject)
                } else {
                    parameters[item.name] = [existValue, value] as AnyObject
                }
                
            } else {
                
                parameters[item.name] = item.value as AnyObject
            }
        })
        
        return parameters
    }
}