iOS设置tabbar的显示之 imageWithRenderingMode：

以下代码是设置选中和未选中的图片设置的方式：

img:未选中图片
selectedImg：选中图片

vc.tabBarItem.image = [UIImage imageNamed:img];    UIImage *imgV4 = [UIImage imageNamed:selectedImg];    vc.tabBarItem.selectedImage = [imgV4 imageWithRenderingMode:UIImageRenderingModeAlwaysTemplate];    [vc.tabBarItem setTitleTextAttributes:[NSDictionary dictionaryWithObjectsAndKeys:[UIColor colorWithWhite:0.286 alpha:1.000], NSForegroundColorAttributeName, nil] forState:UIControlStateNormal];    [vc.tabBarItem setTitleTextAttributes:[NSDictionary dictionaryWithObjectsAndKeys:[UIColor orangeColor], NSForegroundColorAttributeName, nil] forState:UIControlStateSelected];

上面的代码中有：
vc.tabBarItem.selectedImage = [imgV4 imageWithRenderingMode:UIImageRenderingModeAlwaysTemplate]
苹果的官方解释为：Creates and returns a new image object with the specified rendering mode（创建和放回一个指定渲染模式的图片对象）.

渲染模式如下所示：

typedef enum : NSInteger {   UIImageRenderingModeAutomatic,   UIImageRenderingModeAlwaysOriginal,   UIImageRenderingModeAlwaysTemplate,} UIImageRenderingMode;

UIImageRenderingModeAutomaticUse the default rendering mode for the context where the image is used.-根据图片的使用环境和所处的绘图上下文自动调整渲染模Available in iOS 7.0 and later.UIImageRenderingModeAlwaysOriginalAlways draw the original image, without treating it as a template.-始终根据Tint Color绘制图片，忽略图片的颜色信Available in iOS 7.0 and later.UIImageRenderingModeAlwaysTemplateAlways draw the image as a template image, ignoring its color information.-总是画图像作为模板图像,忽视它的颜色信息Available in iOS 7.0 and later.

那么他们的具体区别是什么呢？我们看看以下实验，然后自己可以体会体会。
以下是原始图片：

当我们将模式设置为：UIImageRenderingModeAlwaysOriginal
看到的是如下的样子：

当我们将模式设置为：UIImageRenderingModeAutomatic
看到的是如下的样子：

当我们将模式设置为：UIImageRenderingModeAlwaysTemplate
看到的是如下的样子：

以上就是设置tabbar时图片的渲染模式不同而产生的效果。

对UIImageView中的图片进行渲染的时候效果如下：

UIImageView *igv = [[UIImageView alloc]init];    igv.image = [UIImage imageNamed:@"synchronize_banner_add_friends"];    [igv.image imageWithRenderingMode:UIImageRenderingModeAutomatic];    [self.view addSubview:igv];    UIImageView *igv1 = [[UIImageView alloc]init];    igv1.image = [UIImage imageNamed:@"synchronize_banner_add_friends"];    [igv1.image imageWithRenderingMode:UIImageRenderingModeAlwaysOriginal];    [self.view addSubview:igv1];    UIImageView *igv2 = [[UIImageView alloc]init];    igv2.image = [UIImage imageNamed:@"synchronize_banner_add_friends"];    [igv2.image imageWithRenderingMode:UIImageRenderingModeAlwaysTemplate];    [self.view addSubview:igv2];    CGFloat w = 300;    CGFloat h = 80;    CGFloat offset = 90;    [igv mas_makeConstraints:^(MASConstraintMaker *make) {        make.centerX.mas_equalTo(self.view);        make.centerY.mas_equalTo(-200);        make.width.mas_equalTo(w);        make.height.mas_equalTo(h);    }];    [igv1 mas_makeConstraints:^(MASConstraintMaker *make) {        make.centerX.mas_equalTo(self.view);        make.centerY.mas_equalTo(igv.centerY).with.offset(offset);        make.width.mas_equalTo(w);        make.height.mas_equalTo(h);    }];    [igv2 mas_makeConstraints:^(MASConstraintMaker *make) {        make.centerX.mas_equalTo(self.view);        make.centerY.mas_equalTo(igv1.centerY).with.offset(offset);        make.width.mas_equalTo(w);        make.height.mas_equalTo(h);    }];

发现这里三种模式没有任何的变化。

分别给它们添加上Tint Color之后同样没有发生什么变化。

igv.tintColor = [UIColor redColor];igv1.tintColor = [UIColor redColor];igv2.tintColor = [UIColor redColor];

—先写到这里