iOS 为导航栏自定义按钮图案Button Image 运行出来的颜色与原本颜色不一样 －解决方案

为相机制作闪光灯，在导航栏自定义了“闪光”图案，希望点击时变换图片，但是一直没有改变，原来是因为设置了Global Tint的颜色，所以系统会自动把图片的颜色改为Global Tint的颜色。

解决方案，设置图片时，添加：imageWithRenderingMode:UIImageRenderingModeAlwaysOriginal

源码：

- (void) setFlashOn:(BOOL)isOn
{
if (self.captureDevice.hasFlash) {
UIImage* flashlIcon;
[self.captureDevice lockForConfiguration:nil]; //you must lock before setting torch mode
if (isOn) {
NSLog(@"set flash on");
[self.captureDevice setFlashMode:AVCaptureFlashModeOn];
flashlIcon = [UIImage imageNamed:@"flash_on"];
}
else{
NSLog(@"set flash off");
[self.captureDevice setFlashMode:AVCaptureFlashModeOff];
flashlIcon = [UIImage imageNamed:@"flash_off"];
}
[self.captureDevice unlockForConfiguration];
[self.navigationItem.rightBarButtonItem setImage:[flashlIcon imageWithRenderingMode:UIImageRenderingModeAlwaysOriginal]];
}
else{
NSLog(@"Sorry, this device doesn't have flash.");
}
}

参考：

http://stackoverflow.com/questions/21252194/navigation-bar-button-item-image-color-is-different-when-design-through-xib-of-x