使按钮的前景图像从底部开始

Question

迭代日期单元格并动态设置每个单元格的前景图像

for (int i = 0; i < numDatesSelected; i++) {
    UIButton *myButton = (UIButton *)[self.smallCalendarView viewWithTag:[selectedDates[i] timeIntervalSince1970]];
    float btnWidth = myButton.frame.size.width;
    float btnHeight = (myButton.frame.size.height - (i*3));
    UIImage *img = [self imageWithColor:[UIColor greenColor] width:btnWidth height:btnHeight];
    [myButton setImage:img forState:UIControlStateNormal];
}

}

返回UIImage对象

- (UIImage *)imageWithColor:(UIColor *)color width:(float)w height:(float)h {
    CGRect rect = CGRectMake(0, 0, w, h);
    // Create a w by H pixel context
    UIGraphicsBeginImageContextWithOptions(rect.size, NO, 0);
    [color setFill];
    UIRectFill(rect);   // Fill it with your color
    UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    return image;
}

结果就是这个

我想将所有绿色框放在每个表格单元格的底部。它们现在垂直居中。我该怎么做？谢谢!!

Answer 1

我建议创建与按钮大小相同的图像，并只填充放置在所需位置的内部矩形。

- (UIImage *)imageWithColor:(UIColor *)color totalWidth:(float)tw totalHeight:(float)th filledWidth:(float)fw filledHeight:(float)fh {
    CGRect rect = CGRectMake(0, 0, tw, th);
    // Create a tw by th pixel context
    UIGraphicsBeginImageContextWithOptions(rect.size, NO, 0);
    //Create a inner rect to fill with your color
    CGRect innerRect = CGRectMake(0 , th - fh, fw, fh);
    [color setFill];
    // Fill the inner rect with your color
    UIRectFill(innerRect);  
    UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    return image; 
}