iOS解决工信部规定获取IDFA超频超限问题

IDFA超频超限问题：
原因：检测机构统计IDFA获取频率的方式，通过检测advertisingIdentifier方法被调用次数来判定频率，每调用一次，获取频次+1。
解决思路：
1、添加ASIdentifierManager分类。
2、交换advertisingIdentifier方法。
3、在交换的方法中限制调用advertisingIdentifier的次数；
代码如下：

@implementation ASIdentifierManager (GetIDFA)

+ (void)load {
    GetIDFA_SwizzleMethod([self class], @selector(advertisingIdentifier), @selector(swizzled_advertisingIdentifier));
}

- (NSUUID *)swizzled_advertisingIdentifier {
    NSString *idfaInfoStr = [Keychain secretForKey:@"SYSTEMIDFA"];
    if ([NSObject isNotEmptyString:idfaInfoStr]) {
        NSDictionary *idfaInfoDic = [idfaInfoStr JSONValue];
        if (idfaInfoDic) {
            NSString *idfaStr = [idfaInfoDic stringForKey:@"deviceIdfa"] ?: @"";
            NSInteger getIdfaNum = [[idfaInfoDic stringForKey:@"getDeviceIdfaNum"] integerValue];
            /// 这里限制一下获取的次数如果超过50次，则重新走系统方法获取，防止idfa发生改变。
            if (getIdfaNum < 50 && idfaStr && idfaStr.length > 0) {
                NSUUID *uuid = [[NSUUID alloc] initWithUUIDString:idfaStr];
                getIdfaNum += 1;
                NSDictionary *newIdfaInfoDic = @{@"deviceIdfa": idfaStr, @"getDeviceIdfaNum": [NSString stringWithFormat:@"%ld", getIdfaNum]};
                [PCDKeychain saveSecret:[newIdfaInfoDic JSONRepresentation] forKey:@"SYSTEMIDFA"];
                return uuid;
            }
        }
    }
    NSUUID *systemUUID = [self swizzled_advertisingIdentifier];
    NSDictionary *newIdfaInfoDic = @{@"deviceIdfa": [systemUUID UUIDString], @"getDeviceIdfaNum": @"1"};
    [Keychain saveSecret:[newIdfaInfoDic JSONRepresentation] forKey:@"SYSTEMIDFA"];
    return systemUUID;
}

void GetIDFA_SwizzleMethod(Class class, SEL originalSelector, SEL swizzledSelector) {
    Method originalMethod = class_getInstanceMethod(class, originalSelector);
    Method swizzledMethod = class_getInstanceMethod(class, swizzledSelector);
    BOOL didAddMethod = class_addMethod(class, originalSelector, method_getImplementation(swizzledMethod), method_getTypeEncoding(swizzledMethod));
    if (didAddMethod) {
        class_replaceMethod(class, swizzledSelector, method_getImplementation(originalMethod), method_getTypeEncoding(originalMethod));
    } else {
        method_exchangeImplementations(originalMethod, swizzledMethod);
    }
}
@end

Keychain为框架，可以自行替换。
每50次去调用一次系统获取方法，主要是为了防止IDFA发生改变，不能及时更新到服务器。这里可以自行更改次数，只要不超过1秒/次这个频率，检测机构都不会报超频超限。