Totally lost with this one. Here's my code:
theColor = [NSString stringWithFormat:#"white"];
NSLog(#"%s", theColor);
Which is returing:
†t†å
I must be doing something stupid, but can not figure it out for the life of me.
Change your print to:
NSLog(#"%#", theColor);
Hope it helps.
The thing is that %s expects a C-string (char array with a NULL terminator) and you are passing a NSString instance which is not the same as a C-string. The modifier you need in a format to print NSString content is %#.
%s is for printing C-style strings.
%# is for printing Objective-C objects (like NSString).
BTW: “theColor = [NSString stringWithFormat:#"white"];” – why not “theColor = #"white";”?
Greetings
Related
I'm a little bit confused about the syntax of NSLog. For example,
NSString *nameString = #"Name";
NSLog(#"nameString is: %#", nameString);
If my understanding is correct (which it very well may not be), then nameString is defined to be a pointer to a String. I thought then that this would print the memory address that nameString holds, not the value of that address. So, if that is true, then in the NSLog statement, to get the value of the pointer, shouldn't we need to use the asterisk notation to access what nameString points to like this:
NSLog(#"nameString is: %#", *nameString);
?
It has been a little while since programming in C, but since Objective-C is a superset of C I thought they would behave similarly.
An explanation would be greatly appreciated! Thanks!
The command %# is like "shortcut" that calls the method -description on the receiver. For an NSString it simply display the string itself, since is inherited from NSObject you can override it, very usefull if you create for own class. In that case the default behaviur is print the value of the pointer. If you want to print the address of the pointer in the string just replace with :
NSLog(#"nameString is: %p", nameString)
I think that you use an asterisk only to declare a pointer. Then, you only use the name you decided. For example:
NSString *foo = [[NSString alloc] initWithString:#"Hello"];
NSLog(#"%#", foo);
Correct me if I am wrong :)
It's an object and NSLog is a function that uses its format specifiers to determine what to do with the argument. In this case the specifier is %# which tells NSLog to call a method on an object.
Normally this will call the method "description" which returns an NSString but it probably does respondsToMethod first and falls through to some other string methods.
How to convert a CGPDFStringRef to unicode char? I have used CGPDFStringCopyTextString to get the string and then [string characterAtIndex:i] to cast to unichar, is this the right way? or is there any way to get the bytes of the string and convert to unicode directly?
Need some guidance here.
NSString is capable of handling of unicode characters itself, you just need to convert the CGPDFString to NSString and further you can use it as follows:
NSString *tempStr = (NSString *)CGPDFStringCopyTextString(objectString);
although UPT's answer is correct, it will produce a memory leak
from the documentation:
CGPDFStringCopyTextString
"...You are responsible for releasing this object."
the correct way to do this would be:
CFStringRef _res = CGPDFStringCopyTextString(pdfString);
NSString *result = [NSString stringWithString:(__bridge NSString *)_res];
CFRelease(_res);
It's not a bad idea, even if you can access the CGPDFString directly using CGPDFStringGetBytePtr. You will also need CGPDFStringGetLength to get the string length, as it may not be null-terminated.
See the documentation for more info
I have an NSString which contains data encoded with NSUTF8Encoding. I want to convert that string into NSASCIIEncoding. Please tell me anyway to convert it in a proper manner. I am able to convert reverse (NSASCIIEncoding to NSUTF8Encoding).
Please provide any sample code.
Thanks in advance
I have an NSString which contains data encoded with NSUTF8Encoding.
Really? Because an NSString always treats its contents as UTF-16 internally. Because you cannot be sure how an NSString stores its data internally. Conceptually, NSString works with UTF-16.
I want to convert that string into NSASCIIStringEncoding.
if ([myString canBeConvertedToEncoding:NSASCIIStringEncoding]) {
const char *asciiString = [myString cStringUsingEncoding:NSASCIIStringEncoding];
}
Greetings,
I'm trying to simply compare a NSString to an NSArray.
Here is my code:
NSString *username=uname.text;
NSString *regex=#"^[a-zA-Z0-9-_.]{3,20}$";
NSArray *matchArray=nil;
matchArray=[username componentsMatchedByRegex:regex];
if(matchArray[0] == "asdf"){ //this line causes the problem!
NSLog(#"matchArray %#",matchArray);
}
I get an "invalid operands to binary ==" error.
How can I compare the string?
Many thanks in advance,
You are trying to compare an NSString to a C string (char *), which is wrong. matchArray is an NSArray so you cannot treat it as a C array either, you have to use its objectAtIndex: method and pass in the index.
Use this instead:
if ([[matchArray objectAtIndex:0] isEqualToString:#"asdf"]) {
NSLog(#"matchArray %#", matchArray);
}
Addressing your comments, the reason why isEqualToString: does not show up in autocomplete is because Xcode cannot guess that matchArray contains NSStrings (it only knows it contains ids, that is, arbitrary Objective-C objects). If you really wanted to be sure, you can perform an explicit cast, but it doesn't matter if you don't:
if ([(NSString *)[matchArray objectAtIndex:0] isEqualToString:#"asdf"]) {
NSLog(#"matchArray %#", matchArray);
}
you want to use -objectAtIndex to get the array element. NOT the C array accessor syntax
try to use:
[[matchArray objectAtIndex:0] isEqualToString:#"asdf"];
anyway the string "asdf" should be #"asdf"
I'm trying to extract a string (which contains an integer) from an array and then use it as an int in a function. I'm trying to convert it to a int using intValue.
Here's the code I've been trying.
NSArray *_returnedArguments = [serverOutput componentsSeparatedByString:#":"];
[_appDelegate loggedIn:usernameField.text:passwordField.text:(int)[[_returnedArguments objectAtIndex:2] intValue]];
I get this error:
passing argument 3 of 'loggedIn:::' makes pointer from integer
without a cast
What's wrong?
I really don't know what was so hard about this question, but I managed to do it this way:
[myStringContainingInt intValue];
It should be noted that you can also do:
myStringContainingInt.intValue;
You can just convert the string like that [str intValue] or [str integerValue]
integerValue
Returns the NSInteger value of the receiver’s text.
(NSInteger)integerValue
Return Value
The NSInteger value of the receiver’s text, assuming a decimal representation and skipping whitespace at the beginning of the string. Returns 0 if the receiver doesn’t begin with a valid decimal text representation of a number.
for more information refer here
NSArray *_returnedArguments = [serverOutput componentsSeparatedByString:#":"];
_returnedArguments is an array of NSStrings which the UITextField text property is expecting. No need to convert.
Syntax error:
[_appDelegate loggedIn:usernameField.text:passwordField.text:(int)[[_returnedArguments objectAtIndex:2] intValue]];
If your _appDelegate has a passwordField property, then you can set the text using the following
[[_appDelegate passwordField] setText:[_returnedArguments objectAtIndex:2]];
Basically, the third parameter in loggedIn should not be an integer, it should be an object of some kind, but we can't know for sure because you did not name the parameters in the method call. Provide the method signature so we can see for sure. Perhaps it takes an NSNumber or something.
Keep in mind that international users may be using a decimal separator other than . in which case values can get mixed up or just become nil when using intValue on a string.
For example, in the UK 1.23 is written 1,23, so the number 1.777 would be input by user as 1,777, which, as .intValue, will be 1777 not 1 (truncated).
I've made a macro that will convert input text to an NSNumber based on a locale argument which can be nil (if nil it uses device current locale).
#define stringToNumber(__string, __nullable_locale) (\
(^NSNumber *(void){\
NSLocale *__locale = __nullable_locale;\
if (!__locale) {\
__locale = [NSLocale currentLocale];\
}\
NSString *__string_copy = [__string stringByReplacingOccurrencesOfString:__locale.groupingSeparator withString:#""];\
__string_copy = [__string_copy stringByReplacingOccurrencesOfString:__locale.decimalSeparator withString:#"."];\
return #([__string_copy doubleValue]);\
})()\
)
If I understood you correctly, you need to convert your NSString to int? Try this peace of code:
NSString *stringWithNumberInside = [_returnedArguments objectAtIndex:2];
int number;
sscanf([stringWithNumberInside UTF8String], "%x", &flags);