IOS常用代码整理

1、更改cell选中的背景

UIView *cellView = [[UIView alloc] init];    cellView.frame = CGRectMake(0, 0, 320, 44);    cellView.backgroundColor = [UIColor colorWithPatternImage:[UIImage imageNamed:@"xxx.png"]];  cell.selectedBackgroundView = cellView;

2、截取屏幕图片

UIGraphicsBeginImageContext(CGSizeMake(xxx,xxx));  [self.view.layer renderInContext:UIGraphicsGetCurrentContext()];  UIImage *aImage = UIGraphicsGetImageFromCurrentImageContext();  UIGraphicsEndImageContext();  imageData = UIImagePNGRepresentation(aImage);

3、自定义字符串颜色，拷代码，可直接用

+ (UIColor *) colorWithHexString: (NSString *) stringToConvert    {      NSString *cString = [[stringToConvert stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]] uppercaseString]; //去掉前后空格换行符      // String should be 6 or 8 characters      if ([cString length] < 6) return [UIColor redColor];      // strip 0X if it appears      if ([cString hasPrefix:@"0X"]) cString = [cString substringFromIndex:2];      if ([cString hasPrefix:@"#"]) cString = [cString substringFromIndex:1];      if ([cString length] != 6) return [UIColor redColor];      // Separate into r, g, b substrings      NSRange range;      range.location = 0;      range.length = 2;      NSString *rString = [cString substringWithRange:range];      range.location = 2;      NSString *gString = [cString substringWithRange:range];      range.location = 4;      NSString *bString = [cString substringWithRange:range];      // Scan values      unsigned int r, g, b;      [[NSScanner scannerWithString:rString] scanHexInt:&r];  //扫描16进制到int      [[NSScanner scannerWithString:gString] scanHexInt:&g];      [[NSScanner scannerWithString:bString] scanHexInt:&b];      return [UIColor colorWithRed:((float) r / 255.0f)                             green:((float) g / 255.0f)                              blue:((float) b / 255.0f)                             alpha:1.0f];  }

4、压缩图片，所需参数，需要处理的图片，新图片的size

- (UIImage*)imageWithImageSimple:(UIImage*)image scaledToSize:(CGSize)newSize

{

    UIGraphicsBeginImageContext(newSize);

    [image drawInRect:CGRectMake(0,0,newSize.width,newSize.height)];

    UIImage* newImage = UIGraphicsGetImageFromCurrentImageContext();

    UIGraphicsEndImageContext();

    return newImage;

}

+(CGSize)getSizeForLabel:(NSString *)str fontFamily:(NSString *)fontFamily fontSize:(CGFloat)fontSize width:(NSInteger)labelWidth{      UIFont *font = [UIFontfontWithName:fontFamily size:fontSize];      CGSize size = CGSizeMake(labelWidth,3000);      return [strsizeWithFont:font constrainedToSize:sizelineBreakMode:UILineBreakModeCharacterWrap];  }

6、将data转换成64位的二进制，一般用于图片的上传。

+(NSString*) base64Encode:(NSData *)data  {      static char base64EncodingTable[64] = {          'A', 'B','C', 'D', 'E','F', 'G', 'H','I', 'J', 'K','L', 'M', 'N','O', 'P',          'Q', 'R','S', 'T', 'U','V', 'W', 'X','Y', 'Z', 'a','b', 'c', 'd','e', 'f',          'g', 'h','i', 'j', 'k','l', 'm', 'n','o', 'p', 'q','r', 's', 't','u', 'v',          'w', 'x','y', 'z', '0','1', '2', '3','4', '5', '6','7', '8', '9','+', '/'      };      int length = [data length];      unsigned long ixtext, lentext;      long ctremaining;      unsigned char input[3], output[4];      short i, charsonline = 0, ctcopy;      const unsignedchar *raw;      NSMutableString *result;            lentext = [data length];       if (lentext < 1)          return @"";      result = [NSMutableStringstringWithCapacity: lentext];      raw = [data bytes];      ixtext = 0;             while (true) {          ctremaining = lentext - ixtext;          if (ctremaining <= 0)               break;                  for (i = 0; i <3; i++) {               unsigned long ix = ixtext + i;              if (ix < lentext)                  input[i] = raw[ix];              else                  input[i] = 0;          }          output[0] = (input[0] &0xFC) >> 2;          output[1] = ((input[0] &0x03) << 4) | ((input[1] &0xF0) >> 4);          output[2] = ((input[1] &0x0F) << 2) | ((input[2] &0xC0) >> 6);          output[3] = input[2] &0x3F;          ctcopy = 4;          switch (ctremaining) {              case 1:                   ctcopy = 2;                   break;              case 2:                   ctcopy = 3;                   break;          }                    for (i = 0; i < ctcopy; i++)              [result appendString: [NSStringstringWithFormat: @"%c", base64EncodingTable[output[i]]]];                    for (i = ctcopy; i < 4; i++)              [result appendString: @"="];                    ixtext += 3;          charsonline += 4;                    if ((length > 0) && (charsonline >= length))              charsonline = 0;      }           return result;  }