修改UISearchBar背景

转载：http://blog.csdn.net/favormm/archive/2010/11/30/6045463.aspx

UISearchBar是由两个subView组成的，一个是UISearchBarBackGround,另一个是UITextField. 而IB中没有直接操作背景的属性，在此我总结了几个方法去修改它。

1. 只显示UITextField.采用了layer mask.代码如下：

//first make sure you include core animation so that the compiler will know about your view's layer
#import <QuartzCore/QuartzCore.h>
//now make a mask.  this is basically just a solid colored shape.  When you apply the mask, anywhere where the color is solid will become transparent in your view.  i used the excellent Opacity (http://likethought.com/opacity/) to generate this code, but you can do it any way you'd like
@interface SearchMaskLayer : CALayer {
}
@end
@implementation SearchMaskLayer
- (void)drawInContext:(CGContextRef)context
{

    CGRect imageBounds = CGRectMake(0, 0, 310, 34);
    CGRect bounds = imageBounds;
    CGFloat alignStroke;
    CGFloat resolution;
    CGMutablePathRef path;
    CGPoint point;
    CGPoint controlPoint1;
    CGPoint controlPoint2;
    UIColor *color;
    resolution = 0.5 * (bounds.size.width / imageBounds.size.width + bounds.size.height / imageBounds.size.height);
    CGContextSaveGState(context);
    CGContextTranslateCTM(context, bounds.origin.x, bounds.origin.y);
    CGContextScaleCTM(context, (bounds.size.width / imageBounds.size.width), (bounds.size.height / imageBounds.size.height));
    // Layer 1
    alignStroke = 0.0;
    path = CGPathCreateMutable();
    point = CGPointMake(295.0, 32.0);
    point.x = (round(resolution * point.x + alignStroke) - alignStroke) / resolution;
    point.y = (round(resolution * point.y + alignStroke) - alignStroke) / resolution;
    CGPathMoveToPoint(path, NULL, point.x, point.y);
    point = CGPointMake(310.0, 17.0);
    point.x = (round(resolution * point.x + alignStroke) - alignStroke) / resolution;
    point.y = (round(resolution * point.y + alignStroke) - alignStroke) / resolution;
    controlPoint1 = CGPointMake(303.229, 32.0);
    controlPoint1.x = (round(resolution * controlPoint1.x + alignStroke) - alignStroke) / resolution;
    controlPoint1.y = (round(resolution * controlPoint1.y + alignStroke) - alignStroke) / resolution;
    controlPoint2 = CGPointMake(310.0, 25.229);
    controlPoint2.x = (round(resolution * controlPoint2.x + alignStroke) - alignStroke) / resolution;
    controlPoint2.y = (round(resolution * controlPoint2.y + alignStroke) - alignStroke) / resolution;
    CGPathAddCurveToPoint(path, NULL, controlPoint1.x, controlPoint1.y, controlPoint2.x, controlPoint2.y, point.x, point.y);
    point = CGPointMake(310.0, 17.0);
    point.x = (round(resolution * point.x + alignStroke) - alignStroke) / resolution;
    point.y = (round(resolution * point.y + alignStroke) - alignStroke) / resolution;
    CGPathAddLineToPoint(path, NULL, point.x, point.y);
    point = CGPointMake(295.0, 2.0);
    point.x = (round(resolution * point.x + alignStroke) - alignStroke) / resolution;
    point.y = (round(resolution * point.y + alignStroke) - alignStroke) / resolution;
    controlPoint1 = CGPointMake(310.0, 8.771);
    controlPoint1.x = (round(resolution * controlPoint1.x + alignStroke) - alignStroke) / resolution;
    controlPoint1.y = (round(resolution * controlPoint1.y + alignStroke) - alignStroke) / resolution;
    controlPoint2 = CGPointMake(303.229, 2.0);
    controlPoint2.x = (round(resolution * controlPoint2.x + alignStroke) - alignStroke) / resolution;
    controlPoint2.y = (round(resolution * controlPoint2.y + alignStroke) - alignStroke) / resolution;
    CGPathAddCurveToPoint(path, NULL, controlPoint1.x, controlPoint1.y, controlPoint2.x, controlPoint2.y, point.x, point.y);
    point = CGPointMake(15.0, 2.0);
    point.x = (round(resolution * point.x + alignStroke) - alignStroke) / resolution;
    point.y = (round(resolution * point.y + alignStroke) - alignStroke) / resolution;
    CGPathAddLineToPoint(path, NULL, point.x, point.y);
    point = CGPointMake(0.0, 17.0);
    point.x = (round(resolution * point.x + alignStroke) - alignStroke) / resolution;
    point.y = (round(resolution * point.y + alignStroke) - alignStroke) / resolution;
    controlPoint1 = CGPointMake(6.771, 2.0);
    controlPoint1.x = (round(resolution * controlPoint1.x + alignStroke) - alignStroke) / resolution;
    controlPoint1.y = (round(resolution * controlPoint1.y + alignStroke) - alignStroke) / resolution;
    controlPoint2 = CGPointMake(0.0, 8.771);
    controlPoint2.x = (round(resolution * controlPoint2.x + alignStroke) - alignStroke) / resolution;
    controlPoint2.y = (round(resolution * controlPoint2.y + alignStroke) - alignStroke) / resolution;
    CGPathAddCurveToPoint(path, NULL, controlPoint1.x, controlPoint1.y, controlPoint2.x, controlPoint2.y, point.x, point.y);
    point = CGPointMake(0.0, 17.0);
    point.x = (round(resolution * point.x + alignStroke) - alignStroke) / resolution;
    point.y = (round(resolution * point.y + alignStroke) - alignStroke) / resolution;
    CGPathAddLineToPoint(path, NULL, point.x, point.y);
    point = CGPointMake(15.0, 32.0);
    point.x = (round(resolution * point.x + alignStroke) - alignStroke) / resolution;
    point.y = (round(resolution * point.y + alignStroke) - alignStroke) / resolution;
    controlPoint1 = CGPointMake(0.0, 25.229);
    controlPoint1.x = (round(resolution * controlPoint1.x + alignStroke) - alignStroke) / resolution;
    controlPoint1.y = (round(resolution * controlPoint1.y + alignStroke) - alignStroke) / resolution;
    controlPoint2 = CGPointMake(6.771, 32.0);
    controlPoint2.x = (round(resolution * controlPoint2.x + alignStroke) - alignStroke) / resolution;
    controlPoint2.y = (round(resolution * controlPoint2.y + alignStroke) - alignStroke) / resolution;
    CGPathAddCurveToPoint(path, NULL, controlPoint1.x, controlPoint1.y, controlPoint2.x, controlPoint2.y, point.x, point.y);
    point = CGPointMake(295.0, 32.0);
    point.x = (round(resolution * point.x + alignStroke) - alignStroke) / resolution;
    point.y = (round(resolution * point.y + alignStroke) - alignStroke) / resolution;
    CGPathAddLineToPoint(path, NULL, point.x, point.y);
    CGPathCloseSubpath(path);
    color = [UIColor colorWithRed:0.0 green:0.0 blue:0.0 alpha:1.0];
    [color setFill];
    CGContextAddPath(context, path);
    CGContextFillPath(context);
    CGPathRelease(path);
}
然后在你的controller中应用这个mask layer到你的UISearchBar
- (void)viewDidLoad {
    [super viewDidLoad];
    SearchMaskLayer *maskLayer = [[SearchMaskLayer alloc] init];
    [maskLayer setFrame:CGRectMake(0, 0, 310, 34)];
    [maskLayer setPosition:CGPointMake(162,21)];
    [maskLayer setNeedsDisplay];
    [self.searchBar.layer setNeedsDisplay];
    [self.searchBar.layer setMask:maskLayer];
    [maskLayer release];
}

 

2. 隐藏背景。非官方的方法。

for (UIView *subview in searchBar.subviews) {
    if ([subview isKindOfClass:NSClassFromString(@"UISearchBarBackground")]) {
        [subview removeFromSuperview];
        break;
    }
}

 

3. 改变UISearchBar外观。 你可以子类化或category UISearchBar,然后实现两个方法，见代码。

- (void)drawRect:(CGRect)rect {
//  UIImage *image = [UIImage imageNamed: @"background.png"];
//  [image drawInRect:rect];
}
- (void)drawLayer:(CALayer *)layer inContext:(CGContextRef)ctx {
    UIImage *img = [UIImage imageNamed: @"background.png"];
    UIImageView *v = [[[UIImageView alloc] initWithFrame:CGRectZero] autorelease];
    [v setImage:img];
    v.bounds = CGRectMake(0, 0, img.size.width, img.size.height);
    NSLog([NSString stringWithFormat:@"%f:%f",img.size.width, img.size.height]);
    NSArray *subs = self.subviews;
    for (int i = 0; i < [subs count]; i++) {
        id subv = [self.subviews objectAtIndex:i];
        if ([subv isKindOfClass:NSClassFromString(@"UISearchBarBackground")])
        {
            CGRect viewRect = [subv frame];
            [v setFrame:viewRect];
            [self insertSubview:v atIndex:i];
        }
    }
    [v setNeedsDisplay];
    [v setNeedsLayout];
}

 

UISearchBar也是一个UIView,所以你可以像对待UIView一样对待它。