iphone不规则button

大体思路 如下
检测hit 点击返回来的色值  如果返回是透明 则说明没在button内部

以下为 公共代码
UIImage+ColorAtPixel.h

#import <UIKit/UIKit.h>

@interface UIImage (ColorAtPixel)

- (UIColor *)colorAtPixel:(CGPoint)point;

@end

 UIImage+ColorAtPixel.m

#import <CoreGraphics/CoreGraphics.h>

#import "UIImage+ColorAtPixel.h"

@implementation UIImage (ColorAtPixel)

/*
 Returns the color of the image pixel at point. Returns nil if point lies outside the image bounds.
 If the point coordinates contain decimal parts, they will be truncated.
 
 To get at the pixel data, this method must draw the image into a bitmap context.
 For minimal memory usage and optimum performance, only the specific requested
 pixel is drawn.
 If you need to query pixel colors for the same image repeatedly (e.g., in a loop),
 this approach is probably less efficient than drawing the entire image into memory
 once and caching it.
 */
- (UIColor *)colorAtPixel:(CGPoint)point {
    // Cancel if point is outside image coordinates
    if (!CGRectContainsPoint(CGRectMake(0.0f, 0.0f, self.size.width, self.size.height), point)) {
        return nil;
    }
   
   
    // Create a 1x1 pixel byte array and bitmap context to draw the pixel into.
    // Reference: http://stackoverflow.com/questions/1042830/retrieving-a-pixel-alpha-value-for-a-uiimage
    NSInteger pointX = trunc(point.x);
    NSInteger pointY = trunc(point.y);
    CGImageRef cgImage = self.CGImage;
    NSUInteger width = self.size.width;
    NSUInteger height = self.size.height;
    CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
    int bytesPerPixel = 4;
    int bytesPerRow = bytesPerPixel * 1;
    NSUInteger bitsPerComponent = 8;
    unsigned char pixelData[4] = { 0, 0, 0, 0 };
    CGContextRef context = CGBitmapContextCreate(pixelData,
                                                 1,
                                                 1,
                                                 bitsPerComponent,
                                                 bytesPerRow,
                                                 colorSpace,
                                                 kCGImageAlphaPremultipliedLast | kCGBitmapByteOrder32Big);
    CGColorSpaceRelease(colorSpace);
    CGContextSetBlendMode(context, kCGBlendModeCopy);

    // Draw the pixel we are interested in onto the bitmap context
    CGContextTranslateCTM(context, -pointX, pointY-(CGFloat)height);
    CGContextDrawImage(context, CGRectMake(0.0f, 0.0f, (CGFloat)width, (CGFloat)height), cgImage);
    CGContextRelease(context);
   
    // Convert color values [0..255] to floats [0.0..1.0]
    CGFloat red   = (CGFloat)pixelData[0] / 255.0f;
    CGFloat green = (CGFloat)pixelData[1] / 255.0f;
    CGFloat blue  = (CGFloat)pixelData[2] / 255.0f;
    CGFloat alpha = (CGFloat)pixelData[3] / 255.0f;
    return [UIColor colorWithRed:red green:green blue:blue alpha:alpha];
}

@end

 OBShapedButton.h
#import <UIKit/UIKit.h>
#define kAlphaVisibleThreshold (0.1f)
@interface OBShapedButton : UIButton
{

}

@end

 OBShapedButton.m

#import "OBShapedButton.h"
#import "UIImage+ColorAtPixel.h"
@implementation OBShapedButton

- (BOOL)isAlphaVisibleAtPoint:(CGPoint)point forImage:(UIImage *)image
{
    // Correct point to take into account that the image does not have to be the same size
    // as the button. See https://github.com/ole/OBShapedButton/issues/1
    CGSize iSize = image.size;
    CGSize bSize = self.frame.size;
    point.x *= (bSize.width != 0) ? (iSize.width / bSize.width) : 1;
    point.y *= (bSize.height != 0) ? (iSize.height / bSize.height) : 1;

    CGColorRef pixelColor = [[image colorAtPixel:point] CGColor];
    CGFloat alpha = CGColorGetAlpha(pixelColor);
    return alpha >= kAlphaVisibleThreshold;
}

// UIView uses this method in hitTest:withEvent: to determine which subview should receive a touch event.
// If pointInside:withEvent: returns YES, then the subview’s hierarchy is traversed; otherwise, its branch
// of the view hierarchy is ignored.

- (BOOL)pointInside:(CGPoint)point withEvent:(UIEvent *)event
{
    // Return NO if even super returns NO (i.e., if point lies outside our bounds)
    BOOL superResult = [super pointInside:point withEvent:event];
    if (!superResult) {
        return superResult;
    }

    // We can't test the image's alpha channel if the button has no image. Fall back to super.
    UIImage *buttonImage = [self imageForState:UIControlStateNormal];
    UIImage *buttonBackground = [self backgroundImageForState:UIControlStateNormal];

    if (buttonImage == nil && buttonBackground == nil) {
        return YES;
    }
    else if (buttonImage != nil && buttonBackground == nil) {
        return [self isAlphaVisibleAtPoint:point forImage:buttonImage];
    }
    else if (buttonImage == nil && buttonBackground != nil) {
        return [self isAlphaVisibleAtPoint:point forImage:buttonBackground];
    }
    else {
        if ([self isAlphaVisibleAtPoint:point forImage:buttonImage]) {
            return YES;
        } else {
            return [self isAlphaVisibleAtPoint:point forImage:buttonBackground];
        }
    }
}
@end