runtime精确获取电池电量

- (int)getCurrentBatteryLevel {
    
    UIApplication *app = [UIApplication sharedApplication];
    if (app.applicationState == UIApplicationStateActive||app.applicationState==UIApplicationStateInactive) {
        Ivar ivar = class_getInstanceVariable([app class], "_statusBar");
        id status = object_getIvar(app, ivar);
        for (id aview in [status subviews]) {
            int batteryLevel = 0;
            for (id bview in [aview subviews]) {
                if ([NSStringFromClass([bview class]) caseInsensitiveCompare:@"UIStatusBarBatteryItemView"] == NSOrderedSame
                    && [[[UIDevice currentDevice] systemVersion] floatValue] >= 6.0) {
                    
                    Ivar ivar=  class_getInstanceVariable([bview class],"_capacity");
                    if(ivar) {
                        batteryLevel = ((int (*)(id, Ivar))object_getIvar)(bview, ivar);
                        //这种方式也可以
                        /*ptrdiff_t offset = ivar_getOffset(ivar);
                         unsigned char *stuffBytes = (unsigned char *)(__bridge void *)bview;
                         batteryLevel = *((int *)(stuffBytes + offset));*/
                        NSLog(@"电池电量:%d",batteryLevel);
                        if (batteryLevel > 0 && batteryLevel <= 100) {
                            return batteryLevel;
                        } else {
                            return 0;
                        }
                    }
                }
            }
        }
    }
    return 0;
}