系统会对一些图片进行默认的蓝色渲染

• 设置tabBarItem的选中图片

    vc.tabBarItem.selectedImage = image;

• 设置UIButtonTypeSystem样式按钮的image时

UIButton *btn = [UIButton buttonWithType:UIButtonTypeSystem];
[btn setImage:image forState:UIControlStateNormal];

• 解决方案1：代码产生一张不会进行渲染的图片

// 加载图片
UIImage *tempImage = [UIImage imageNamed:@"tabBar_essence_click_icon"];

// 产生一张不会进行自动渲染的图片
UIImage *selectedImage = [tempImage imageWithRenderingMode:UIImageRenderingModeAlwaysOriginal];
vc.tabBarItem.selectedImage = selectedImage;

• 解决方案2：进行不渲染的设置
• Assets -> 选中图片 -> Render As -> Original Image