NSString dataUsingEncoding allowLossyConversion example ios

[NSString dataUsingEncoding allowLossyConversion]

Returns an NSData object containing a representation of the receiver encoded using a given encoding.

- (NSData *)dataUsingEncoding:(NSStringEncoding)encoding allowLossyConversion:(BOOL)flag

Parameters

encoding

A string encoding.

flag

If YES, then allows characters to be removed or altered in conversion.

Return Value of [NSString dataUsingEncoding allowLossyConversion]

An NSData object containing a representation of the receiver encoded using encoding. Returns nil if flag is NO and the receiver can’t be converted without losing some information (such as accents or case).

Discussion of [NSString dataUsingEncoding allowLossyConversion]

If flag is YES and the receiver can’t be converted without losing some information, some characters may be removed or altered in conversion. For example, in converting a character from NSUnicodeStringEncoding toNSASCIIStringEncoding, the character ‘Á’ becomes ‘A’, losing the accent.

This method creates an external representation (with a byte order marker, if necessary, to indicate endianness) to ensure that the resulting NSData object can be written out to a file safely. The result of this method, when lossless conversion is made, is the default “plain text” format for encoding and is the recommended way to save or transmit a string object.

Example of [NSString dataUsingEncoding allowLossyConversion]

NSString *myAccentStr = @"José";
char str[[myAccentStr length] + 1];

// NSString * to C String (char*)
NSData *strData = [myAccentStr dataUsingEncoding:NSMacOSRomanStringEncoding 
                                allowLossyConversion:YES];
memcpy(str, [strData bytes], [strData length] + 1);
str[[myAccentStr length]] = '\0';
NSLog(@"str (from NSString* to c string): %s", str);

// C String (char*) to NSString *   
NSString *newAccentStr = [NSString stringWithCString:str 
                                            encoding:NSMacOSRomanStringEncoding];
NSLog(@"newAccentStr (from c string to NSString*):  %@", newAccentStr);

Example of [NSString dataUsingEncoding allowLossyConversion]

NSString *geoXValue = @"1.2343243";
NSString *geoYValue = @"1.5646546";

NSString *post = [NSString stringWithFormat:@"geoX%@ geoY%@", geoXValue, geoYValue];

NSData *postData = [post dataUsingEncoding:NSUTF8StringEncoding allowLossyConversion:NO];

Example of [NSString dataUsingEncoding allowLossyConversion]

// original string
NSString *str = @"ÁlgeBra";

// convert to a data object, using a lossy conversion to ASCII
NSData *asciiEncoded = [str dataUsingEncoding:NSASCIIStringEncoding
                         allowLossyConversion:YES];

// take the data object and recreate a string using the lossy conversion
NSString *other = [[NSString alloc] initWithData:asciiEncoded
                                        encoding:NSASCIIStringEncoding];
// relinquish ownership
[other autorelease];

// create final capitalized string
NSString *final = [other capitalizedString];