TMQueryItem.h

#import <Foundation/Foundation.h>

/**
 *  A stand-in for `NSURLQueryItem` that can be used on iOS 7.
 */
@interface TMURLQueryItem : NSObject

/**
 *  @see `NSURLQueryItem`
 */
@property (nonatomic, readonly) NSString *name;

/**
 *  @see `NSURLQueryItem`
 */
@property (nonatomic, readonly) NSString *value;

/**
 *  @see `NSURLQueryItem`
 */
+ (instancetype)queryItemWithName:(NSString *)name value:(NSString *)value;

/**
 *  @see `NSURLQueryItem`
 */
- (instancetype)initWithName:(NSString *)name value:(NSString *)value;

@end

/**
 *  A stand-in for `NSURLComponents` that can be used on iOS 7. Really should only be used if the caller wants to set
 *  `queryItems`.
 */
@interface TMURLComponents : NSObject

/**
 *  @see `NSURLComponents`
 */
@property (nonatomic, readonly) NSURL *URL;

/**
 *  @see `NSURLComponents`
 */
@property (nonatomic, copy) NSArray/*<TMURLQueryItem>*/ *queryItems;

/**
 *  @see `NSURLComponents`
 */
- (instancetype)initWithURL:(NSURL *)URL resolvingAgainstBaseURL:(BOOL)resolve;

@end

TMQueryItem.m

#import "TMURLComponents.h"

static inline bool IS_RUNNING_IOS_8_OR_GREATER() {
    return [[UIDevice currentDevice].systemVersion floatValue] >= 8.0;
}

@implementation TMURLQueryItem

+ (instancetype)queryItemWithName:(NSString *)name value:(NSString *)value {
    return [[[self class] alloc] initWithName:name value:value];
}

- (instancetype)initWithName:(NSString *)name value:(NSString *)value {
    self = [super init];
    if (self) {
        _name = [name copy];
        _value = [value copy];
    }

    return self;
}

@end

@interface TMURLComponents ()

@property (nonatomic, readonly) NSURLComponents *components;

@end

@implementation TMURLComponents

#pragma mark - Initialization

- (instancetype)initWithURL:(NSURL *)URL resolvingAgainstBaseURL:(BOOL)resolve {
    NSParameterAssert(URL);

    NSURLComponents *components = [[NSURLComponents alloc] initWithURL:URL resolvingAgainstBaseURL:resolve];

    if (!components) {
        return nil;
    }

    self = [super init];
    if (self) {
        _components = components;

        [self updateQueryItemsWithComponents];
    }

    return self;
}

- (instancetype)init {
    return [self initWithURL:nil resolvingAgainstBaseURL:NO];
}

#pragma mark - TMURLComponents

- (NSURL *)URL {
    return self.components.URL;
}

#pragma mark - Properties

- (void)setQueryItems:(NSArray *)queryItems {
    _queryItems = [queryItems copy];
    [self updateComponentsWithQueryItems];
}

#pragma mark - Private

- (void)updateQueryItemsWithComponents {
    self.queryItems = ^{
        NSMutableArray *newQueryItems = [NSMutableArray arrayWithCapacity:self.queryItems.count];

        if (IS_RUNNING_IOS_8_OR_GREATER()) {
            for (NSURLQueryItem *item in self.components.queryItems) {
                [newQueryItems addObject:[TMURLQueryItem queryItemWithName:item.name value:item.value]];
            }
        }
        else {
            NSArray *keyValuePairs = [self.components.query componentsSeparatedByString:@"&"];

            for (NSString *keyValuePair in keyValuePairs) {
                NSArray/*<NSString>*/ *keyAndValue = [keyValuePair componentsSeparatedByString:@"="];

                [newQueryItems addObject:[TMURLQueryItem queryItemWithName:keyAndValue.firstObject value:keyAndValue.lastObject]];
            }
        }

        return newQueryItems;
    }();
}

- (void)updateComponentsWithQueryItems {
    NSMutableArray *iteratedItemsContainer = [[NSMutableArray alloc] initWithCapacity:[self.queryItems count]];

    if (IS_RUNNING_IOS_8_OR_GREATER()) {
        for (TMURLQueryItem *item in self.queryItems) {
            [iteratedItemsContainer addObject:[NSURLQueryItem queryItemWithName:item.name value:item.value]];
        }

        self.components.queryItems = iteratedItemsContainer;
    }
    else {
        for (TMURLQueryItem *item in self.queryItems) {
            [iteratedItemsContainer addObject:[NSString stringWithFormat:@"%@=%@", item.name, item.value]];
        }

        self.components.query = [iteratedItemsContainer componentsJoinedByString:@"&"];
    }
}

@end