我的GA反射崩溃问题

#import <Foundation/Foundation.h>

@interface MYGAI : NSObject

@property (nonatomic,strong) id ga;

- (void)trackEventWithCategory:(NSString *)category

                    withAction:(NSString *)action

                     withLabel:(NSString *)label

                     withValue:(NSNumber *)value;

@end

#import "MYGAI.h"

@implementation MYGAI

- (id)init

{

    self = [super init];

    if (self) {

        Class GAIClass = NSClassFromString(@"GAI");

        id gaInstance = [GAIClass performSelector:@selector(sharedInstance)];

        self.ga = [gaInstance valueForKey:@"defaultTracker"];

    }

    return self;

}

- (void)trackEventWithCategory:(NSString *)category

                    withAction:(NSString *)action

                     withLabel:(NSString *)label

                     withValue:(NSNumber *)value

{

    if (self.ga) {

        Class GAIBuilder = NSClassFromString(@"GAIDictionaryBuilder");

        if (!GAIBuilder) {

            NSLog(@"GA统计失败---------请确保您使用的GAI Lib版本是3.0以上!");

            

            NSException *exception = [NSException exceptionWithName:@"GA统计失败" reason:@"请确保您使用的GAI Lib版本是3.0以上!" userInfo:nil];

            @throw exception;

            

            return;

        }

        SEL createEvent = NSSelectorFromString(@"createEventWithCategory:action:label:value:");

        

        NSInvocation *inv = [NSInvocation invocationWithMethodSignature:[GAIBuilder methodSignatureForSelector:createEvent]];

        [inv setSelector:createEvent];

        [inv setTarget:GAIBuilder];

        [inv setArgument:&category atIndex:2];

        [inv setArgument:&action atIndex:3];

        [inv setArgument:&label atIndex:4];

        [inv setArgument:&value atIndex:5];

        [inv invoke];

        

// id gaiBuilder = nil;

        __weak id gaiBuilder = nil;   //这个地方如果不加 __weak 会导致崩溃(我的项目是ARC的)

        [inv getReturnValue:&gaiBuilder];

        

        NSDictionary *dict = [gaiBuilder performSelector:@selector(build)];

        SEL sendAction = NSSelectorFromString(@"send:");

        

        NSInvocation *invView = [NSInvocation invocationWithMethodSignature:[self.ga methodSignatureForSelector:sendAction]];

        [invView setSelector:sendAction];

        [invView setTarget:self.ga];

        [invView setArgument:&dict atIndex:2];

        [invView invoke];

        

        NSLog(@"－----GAsdk统计走完－－");

    }

    else{

        NSLog(@"－－－ga为空－－－gasdk统计失败");

    }

}

@end