图片处理

头像图片处理，没有图片时将姓名的首字母显示到图片上

/*
NSString *name = @"name";
// 获取姓名首字母
NSString *charStr = [self transformToPinyin:name];
UIImage *img = [self getImage:charStr];
imageV.image = img;
*/

• (NSString *)transformToPinyin:(NSString *)name {
  NSMutableString *mutableString = [NSMutableString stringWithString:name];
  CFStringTransform((CFMutableStringRef)mutableString, NULL, kCFStringTransformToLatin, false);
  mutableString = (NSMutableString *)[mutableString stringByFoldingWithOptions:NSDiacriticInsensitiveSearch locale:[NSLocale currentLocale]];
  NSString *tempStr = [mutableString stringByReplacingOccurrencesOfString:@"'" withString:@""];
  NSArray *arr = [tempStr componentsSeparatedByString:@" "];
  NSString *s = @"";
  for (NSString *str in arr) {
  s = [s stringByAppendingString:[str substringToIndex:1]];
  }
  s = [s uppercaseString];
  if (s.length >= 2) {
  s = [s substringToIndex:2];
  }
  return s;
  }

• (UIImage *)getImage:(NSString *)name
  {
  UIColor *color = [self randomColor]; //获取随机颜色
  CGRect rect = CGRectMake(0.0f, 0.0f, 24, 24);
  UIGraphicsBeginImageContext(rect.size);
  CGContextRef context = UIGraphicsGetCurrentContext();
  CGContextSetFillColorWithColor(context, [color CGColor]);
  CGContextFillRect(context, rect);
  UIImage *img = UIGraphicsGetImageFromCurrentImageContext();
  UIGraphicsEndImageContext();

  NSString *headerName = nil;
  if (name.length < 3) {
  headerName = name;
  }else{
  headerName = [name substringFromIndex:name.length-2];
  }
  UIImage *headerimg = [self imageToAddText:img withText:headerName];
  return headerimg;
  }

//随机颜色

• (UIColor *)randomColor
  {
  CGFloat hue = ( arc4random() % 256 / 256.0 ); //0.0 to 1.0
  CGFloat saturation = ( arc4random() % 128 / 256.0 ) + 0.5; // 0.5 to 1.0,away from white
  CGFloat brightness = ( arc4random() % 128 / 256.0 ) + 0.5;
  return [UIColor colorWithHue:hue saturation:saturation brightness:brightness alpha:1];
  }

//把文字绘制到图片上

• (UIImage *)imageToAddText:(UIImage *)img withText:(NSString *)text
  {
  //1.获取上下文
  UIGraphicsBeginImageContext(img.size);
  //2.绘制图片
  [img drawInRect:CGRectMake(0, 0, img.size.width, img.size.height)];
  //3.绘制文字
  CGRect rect = CGRectMake(0,2, img.size.width, img.size.height - 8);
  NSMutableParagraphStyle *style = [[NSMutableParagraphStyle defaultParagraphStyle] mutableCopy];
  style.alignment = NSTextAlignmentCenter;
  //文字的属性
  NSDictionary *dic = @{NSFontAttributeName:[UIFont systemFontOfSize:15],NSParagraphStyleAttributeName:style,NSForegroundColorAttributeName:[UIColor whiteColor]};
  //将文字绘制上去
  [text drawInRect:rect withAttributes:dic];
  //4.获取绘制到得图片
  UIImage *watermarkImg = UIGraphicsGetImageFromCurrentImageContext();
  //5.结束图片的绘制
  UIGraphicsEndImageContext();

  return watermarkImg;
  }