先上效果图:

这个程序分2个层次，一个是顶部的带UITextField的bar,一个是下拉选择的view,下拉选择的view带有4个自定义的UIView

我们先定义一个UIViewController叫MyViewController,然后顶部的bar叫TopBarView,下拉选择的view叫TypeSelectView，像UIButton的自定义的view叫做TypeView

TypeView有两种状态，如果手指触摸到的item就是选中状态，所以TypeSelectView应该有个属性表示当前是哪个view被选中了，TypeView中有个属性叫做自己是否被选中

因为下拉框有收起和展示两种状态，所以TypeSelectedView有个属性表示自己现在在哪种状态

先来写TypeView：

#define TypeView_Width 76
#define TypeView_Height 76

@class TypeSelectView;
@interface TypeView : UIView
@property (nonatomic, assign) int typeId;
@property (nonatomic, assign) BOOL bSelected;
@property (nonatomic,strong) TypeSelectView *typesView;
@end

-(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event{
    if (!_bSelected) {//如果触摸到的这项没被选中，那么我们就要把TypeSelectView中的当前选中项的选中状态取消
        if (_typesView.curSelectedView) {
            _typesView.curSelectedView.bSelected = NO;
            [_typesView.curSelectedView setNeedsDisplay];
        }
        _bSelected = YES;
        _typesView.curSelectedView = self;
        [self setNeedsDisplay];
        
    }
}

- (void)drawRect:(CGRect)rect
{
    CGContextRef context = UIGraphicsGetCurrentContext();
    CGContextSetFillColorWithColor(context, [CCommon RGBColorFromHexString:@"#c5c4cc" alpha:1.0f].CGColor);
    CGFontRef contextFont = CGFontCreateWithFontName((CFStringRef)[UIFont systemFontOfSize:14].fontName);
    CGContextSetFont(context, contextFont);
    
    CFRelease(contextFont);
    CGContextSetFontSize(context, 14.0);
    
    if (_bSelected) {
        //显示select的背景
        UIImage* bgImage = [UIImage imageNamed:@"change_icon_touch_bg.png"];
        CGRect bgRc = rect;
        bgRc.origin.x = (bgRc.size.width - bgImage.size.width)/2+1.0f; //找到背景图image的左上角的x坐标
        bgRc.origin.y = (bgRc.size.height - bgImage.size.height)/2;  <span style="font-family: Arial, Helvetica, sans-serif;">//找到背景图image的左上角的y坐标</span>
        bgRc.size = bgImage.size;  //ui给的背景图的大小作为控件的大小
        [bgImage drawInRect:bgRc];
        
        CGContextSetFillColorWithColor(context, [CCommon RGBColorFromHexString:@"#58baff" alpha:1.0f].CGColor);  //中间填充颜色
    }
    
    //draw image
    NSString* imageName = [NSString string];
    NSString* text = [NSString string];
    
    imageName = @"mbWWW.png";
    if (_typeId == 0) {
        text = @"web";
    }else if(_typeId == 1){
        text = @"weibo";
    }else if(_typeId == 2) {
        text = @"sina";
    }else if(_typeId == 3){
        text = @"sohu";
    }

    if (_bSelected) {
        imageName = [imageName stringByReplacingOccurrencesOfString:@".png" withString:@"_touch.png"];
    }
     //imageName给的view里面的src image的名称，有选中和没选中两种状态
    UIImage* typeImage = [UIImage imageNamed:imageName];
    CGRect rc = rect;
    rc.origin.x = (rc.size.width - typeImage.size.width) / 2;
    rc.origin.y = 10;
    rc.size = typeImage.size;
    [typeImage drawInRect:rc];
    
    //draw text 因为文字在image下面
    CGPoint textPt = CGPointMake(rc.origin.x, rc.origin.y+rc.size.height+10);
    
    
    [text drawAtPoint:textPt withFont:[UIFont systemFontOfSize:14.0f]];
}