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个自己定义的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的自己定义的view叫做TypeView

TypeView有两种状态，假设手指触摸到的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

由于下拉框有收起和展示两种状态。所以TypeSelectedView有个属性表示自己如今在哪种状态

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

touch事件:

-(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event{

    if (!_bSelected) {//假设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];

    }

}

然后是draw:

- (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 由于文字在image以下

    CGPoint textPt = CGPointMake(rc.origin.x, rc.origin.y+rc.size.height+10);

    [text drawAtPoint:textPt withFont:[UIFont systemFontOfSize:14.0f]];

}

代码能够在http://download.csdn.net/detail/baidu_nod/7644329下载