iOS开发小技巧

.UITableView的plain样式下，取消区头停滞效果

• (void)scrollViewDidScroll:(UIScrollView *)scrollView
  {
  CGFloat sectionHeaderHeight = sectionHead.height;
  if (scrollView.contentOffset.y=0)
  {
  scrollView.contentInset = UIEdgeInsetsMake(-scrollView.contentOffset.y, 0, 0, 0);
  }
  else if(scrollView.contentOffset.y>=sectionHeaderHeight)
  {
  scrollView.contentInset = UIEdgeInsetsMake(-sectionHeaderHeight, 0, 0, 0);
  }
  }

iOS 获取汉字的拼音

• (NSString )transform:(NSString )chinese
  {
  //将NSString装换成NSMutableString
  NSMutableString *pinyin = [chinese mutableCopy];
  //将汉字转换为拼音(带音标)
  CFStringTransform((bridge CFMutableStringRef)pinyin, NULL, kCFStringTransformMandarinLatin, NO);
  NSLog(@”%@”, pinyin);
  //去掉拼音的音标
  CFStringTransform((bridge CFMutableStringRef)pinyin, NULL, kCFStringTransformStripCombiningMarks, NO);
  NSLog(@”%@”, pinyin);
  //返回最近结果
  return pinyin;
  }

//阿拉伯数字转中文格式

• (NSString )translation:(NSString )arebic
  {
  NSString str = arebic;
  NSArray arabic_numerals = @[@”1”,@”2”,@”3”,@”4”,@”5”,@”6”,@”7”,@”8”,@”9”,@”0”];
  NSArray chinese_numerals = @[@”一”,@”二”,@”三”,@”四”,@”五”,@”六”,@”七”,@”八”,@”九”,@”零”];
  NSArray digits = @[@”个”,@”十”,@”百”,@”千”,@”万”,@”十”,@”百”,@”千”,@”亿”,@”十”,@”百”,@”千”,@”兆”];
  NSDictionary dictionary = [NSDictionary dictionaryWithObjects:chinese_numerals forKeys:arabic_numerals];
  NSMutableArray sums = [NSMutableArray array];
  for (int i = 0; i < str.length; i ++) {
  NSString substr = [str substringWithRange:NSMakeRange(i, 1)];
  NSString a = [dictionary objectForKey:substr];
  NSString b = digits[str.length -i-1];
  NSString sum = [a stringByAppendingString:b];
  if ([a isEqualToString:chinese_numerals[9]])
  {
  if([b isEqualToString:digits[4]] || [b isEqualToString:digits[8]])
  {
  sum = b;
  if ([[sums lastObject] isEqualToString:chinese_numerals[9]])
  {
  [sums removeLastObject];
  }
  }else
  {
  sum = chinese_numerals[9];
  }
  if ([[sums lastObject] isEqualToString:sum])
  {
  continue;
  }
  }

[sums addObject:sum];
}
NSString sumStr = [sums componentsJoinedByString:@””];
NSString chinese = [sumStr substringToIndex:sumStr.length-1];
NSLog(@”%@”,str);
NSLog(@”%@”,chinese);
return chinese;
}

图片添加水印
-(UIImage )aspjpegImage:(UIImage )img withWord:(NSString )word
{
NSString mark = word;

int w = img.size.width;

int h = img.size.height;
//UIGraphicsBeginImageContext创建一个基于位图的上下文(context),并将其设置为当前上下文(context)
UIGraphicsBeginImageContext(img.size);

[img drawInRect:CGRectMake(0, 0, w, h)];

NSDictionary *attr = @{

NSFontAttributeName: [UIFont boldSystemFontOfSize:20], //设置字体

NSForegroundColorAttributeName : [UIColor redColor] //设置字体颜色

};
//文本绘制 attr代表文本属性
[mark drawInRect:CGRectMake(0, 10, 100, 50) withAttributes:attr]; //左上角

[mark drawInRect:CGRectMake(w - 200, 10, 200, 50) withAttributes:attr]; //右上角

[mark drawInRect:CGRectMake(w - 200, h - 50 - 10, 200, 50) withAttributes:attr]; //右下角

[mark drawInRect:CGRectMake(0, h - 50 - 10, 200, 50) withAttributes:attr]; //左下角

UIImage *newImg = UIGraphicsGetImageFromCurrentImageContext();

UIGraphicsEndImageContext();

return newImg;

}

取上整与取下整
floor(x),有时候也写做Floor(x)，其功能是“下取整”，即取不大于x的最大整数 例如：
x=3.14，floor(x)=3
y=9.99999，floor(y)=9
与floor函数对应的是ceil函数，即上取整函数。

ceil函数的作用是求不小于给定实数的最小整数。
ceil(2)=ceil(1.2)=cei(1.5)=2.00
floor函数与ceil函数的返回值均为double型

给UIView设置图片
UIImage *image = [UIImage imageNamed:@”image”];
self.MYView.layer.contents = (__bridge id _Nullable)(image.CGImage);
self.MYView.layer.contentsRect = CGRectMake(0, 0, 0.5, 0.5);

41.防止scrollView手势覆盖侧滑手势
[scrollView.panGestureRecognizerrequireGestureRecognizerToFail:self.navigationController.interactivePopGestureRecognizer];

//字符串中是否含有中文

• (BOOL)checkIsChinese:(NSString *)string
  {
  for (int i=0; i<string.length; i++)
  {
  unichar ch = [string characterAtIndex:i];
  if (0x4E00 <= ch && ch <= 0x9FA5)
  {
  return YES;
  }
  }
  return NO;
  }