修改ios键盘颜色

Phone和iPod touch的键盘颜色其实是可以通过代码更改的，这样能更匹配App的界面风格，下面是改变iPhone键盘颜色的代码。
1、只有Number Pad和Phone Pad这两种数字键盘才有效果
2、设置Appearance为Alert

- (void)textFieldDidBeginEditing:(UITextField *)textField{ 
    NSArray *ws = [[UIApplication sharedApplication] windows]; 
    for(UIView *w in ws){ 
        NSArray *vs = [w subviews]; 
        for(UIView *v in vs){ 
            if([[NSString stringWithUTF8String:object_getClassName(v)] isEqualToString:@"UIPeripheralHostView"]){ 
                v.backgroundColor = [UIColor redColor]; 
            } 
        } 
    } 
}