由于项目需要，要求获取iOS手机电池电量的详细值以及变化量等信息。所以做了相关的技术调研，实现的方法有很多。所以写了这篇总结，对于当前获取电池电量的方式进行一个整理。

方法一:通过苹果给的api获取

最简单的方式

UIDevice currentDevice].batteryMonitoringEnabled = YES;  
double deviceLevel = [UIDevice currentDevice].batteryLevel; 

另外一种写法

[UIDevice currentDevice].batteryMonitoringEnabled = YES;
[[NSNotificationCenter defaultCenter]addObserverForName:UIDeviceBatteryLevelDidChangeNotification object:nil queue:[NSOperationQueue mainQueue] usingBlock:^(NSNotification*notification) {
      NSLog(@"电池电量：%.2f", [UIDevice currentDevice].batteryLevel);  
 }];

测试多次会出现偏差1%左右，也就是说, 这个办法是存在缺陷的, 最起码, 它不精确。

方法二：通过runtime 获取StatusBar上电池电量控件类私有变量的值，此方法可精准获取iOS6以上电池电量

- (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;
}

方法三：找到Mac下IOKit.framework，将IOKit.framework里面的IOPowerSources.h和IOPSKeys.h拷贝到你的iOS项目中。另外, 还需要把IOKit也导入到你的工程中去，此方法也会出现偏差，不精确。

-(double)getCurrentBatteryLevel  
{  

//Returns a blob of Power Source information in an opaque CFTypeRef.  
CFTypeRef blob = IOPSCopyPowerSourcesInfo();  

//Returns a CFArray of Power Source handles, each of type CFTypeRef.  
CFArrayRef sources = IOPSCopyPowerSourcesList(blob);  

CFDictionaryRef pSource = NULL;  
const void *psValue;  

//Returns the number of values currently in an array.  
int numOfSources = CFArrayGetCount(sources);  

//Error in CFArrayGetCount  
if (numOfSources == 0)  
{  
    NSLog(@"Error in CFArrayGetCount");  
    return -1.0f;  
}  

//Calculating the remaining energy  
for (int i = 0 ; i < numOfSources ; i++)  
{  
    //Returns a CFDictionary with readable information about the specific power source.  
    pSource = IOPSGetPowerSourceDescription(blob, CFArrayGetValueAtIndex(sources, i));  
    if (!pSource)  
    {  
        NSLog(@"Error in IOPSGetPowerSourceDescription");  
        return -1.0f;  
    }  
    psValue = (CFStringRef)CFDictionaryGetValue(pSource, CFSTR(kIOPSNameKey));  

    int curCapacity = 0;  
    int maxCapacity = 0;  
    double percent;  

    psValue = CFDictionaryGetValue(pSource, CFSTR(kIOPSCurrentCapacityKey));  
    CFNumberGetValue((CFNumberRef)psValue, kCFNumberSInt32Type, &curCapacity);  

    psValue = CFDictionaryGetValue(pSource, CFSTR(kIOPSMaxCapacityKey));  
    CFNumberGetValue((CFNumberRef)psValue, kCFNumberSInt32Type, &maxCapacity);  

    percent = ((double)curCapacity/(double)maxCapacity * 100.0f);  

    return percent;  
}  
return -1.0f;  
}

上面的方法都只能获取到电池电量所占百分比，不能获取到实际的电池电量毫安时。