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+-- Forum: Coding (https://zeroday.vip/Forum-Coding)
+--- Forum: Objective-C (https://zeroday.vip/Forum-Objective-C)
+--- Thread: Shortcuts in Objective-C to concatenate NSStrings (/Thread-Shortcuts-in-Objective-C-to-concatenate-NSStrings)
Shortcuts in Objective-C to concatenate NSStrings - serenarghhdj - 07-21-2023
Are there any shortcuts to (`stringByAppendingString:`) string concatenation in Objective-C, or shortcuts for working with `NSString` in general?
For example, I'd like to make:
NSString *myString = @"This";
NSString *test = [myString stringByAppendingString:@" is just a test"];
something more like:
string myString = "This";
string test = myString + " is just a test";
RE: Shortcuts in Objective-C to concatenate NSStrings - ose331 - 07-21-2023
The only way to make `c = [a stringByAppendingString: b]` any shorter is to use autocomplete at around the `st` point. The `+` operator is part of C, which doesn't know about Objective-C objects.
RE: Shortcuts in Objective-C to concatenate NSStrings - maloryemrqpy - 07-21-2023
NSString *label1 = @"Process Name: ";
NSString *label2 = @"Process Id: ";
NSString *processName = [[NSProcessInfo processInfo] processName];
NSString *processID = [NSString stringWithFormat:@"%d", [[NSProcessInfo processInfo] processIdentifier]];
NSString *testConcat = [NSString stringWithFormat:@"%@ %@ %@ %@", label1, processName, label2, processID];
RE: Shortcuts in Objective-C to concatenate NSStrings - erector473 - 07-21-2023
NSString *label1 = @"Process Name: ";
NSString *label2 = @"Process Id: ";
NSString *processName = [[NSProcessInfo processInfo] processName];
NSString *processID = [NSString stringWithFormat:@"%d", [[NSProcessInfo processInfo] processIdentifier]];
NSString *testConcat = [NSString stringWithFormat:@"%@ %@ %@ %@", label1, processName, label2, processID];
RE: Shortcuts in Objective-C to concatenate NSStrings - sethfnb - 07-21-2023
This is for better logging, and logging only - based on dicius excellent multiple argument method. I define a Logger class, and call it like so:
[Logger log: @"foobar ", @" asdads ", theString, nil];
Almost good, except having to end the var args with "nil" but I suppose there's no way around that in Objective-C.
Logger.h
@interface Logger : NSObject {
}
+ (void) log: (id) first, ...;
@end
Logger.m
@implementation Logger
+ (void) log: (id) first, ...
{
// TODO: make efficient; handle arguments other than strings
// thanks to @diciu
[To see links please register here]
NSString * result = @"";id eachArg;
va_list alist;
if(first)
{
result = [result stringByAppendingString:first];
va_start(alist, first);
while (eachArg = va_arg(alist, id))
{
result = [result stringByAppendingString:eachArg];
}
va_end(alist);
}
NSLog(@"%@", result);
}
@end
In order to only **concat** strings, I'd define a Category on NSString and add a static (+) concatenate method to it that looks exactly like the log method above except it returns the string. It's on NSString because it's a string method, and it's static because you want to create a new string from 1-N strings, not call it on any one of the strings that are part of the append.
RE: Shortcuts in Objective-C to concatenate NSStrings - reginaldreginauld966 - 07-21-2023
When building requests for web services, I find doing something like the following is very easy and makes concatenation readable in Xcode:
NSString* postBody = {
@"<?xml version=\"1.0\" encoding=\"utf-8\"?>"
@"<soap:Envelope xmlns:xsi=\"http://www.w3.org/2001/XMLSchema-instance\" xmlns:xsd=\"http://www.w3.org/2001/XMLSchema\" xmlns:soap=\"http://schemas.xmlsoap.org/soap/envelope/\">"
@" <soap:Body>"
@" <WebServiceMethod xmlns=\"\">"
@" <parameter>test</parameter>"
@" </WebServiceMethod>"
@" </soap:Body>"
@"</soap:Envelope>"
};
RE: Shortcuts in Objective-C to concatenate NSStrings - dowieite77736 - 07-21-2023
Well, as colon is kind of special symbol, but *is* part of method signature, it is possible to exted the `NSString` with category to add this **non-idiomatic** style of string concatenation:
[@"This " : @"feels " : @"almost like " : @"concatenation with operators"];
You can define as many colon separated arguments as you find useful... ;-)
For a good measure, I've also added `concat:` with variable arguments that takes `nil` terminated list of strings.
// NSString+Concatenation.h
#import <Foundation/Foundation.h>
@interface NSString (Concatenation)
- (NSString *):(NSString *)a;
- (NSString *):(NSString *)a :(NSString *)b;
- (NSString *):(NSString *)a :(NSString *)b :(NSString *)c;
- (NSString *):(NSString *)a :(NSString *)b :(NSString *)c :(NSString *)d;
- (NSString *)concat:(NSString *)strings, ...;
@end
// NSString+Concatenation.m
#import "NSString+Concatenation.h"
@implementation NSString (Concatenation)
- (NSString *):(NSString *)a { return [self stringByAppendingString:a];}
- (NSString *):(NSString *)a :(NSString *)b { return [[self:a]:b];}
- (NSString *):(NSString *)a :(NSString *)b :(NSString *)c
{ return [[[self:a]:b]:c]; }
- (NSString *):(NSString *)a :(NSString *)b :(NSString *)c :(NSString *)d
{ return [[[[self:a]:b]:c]:d];}
- (NSString *)concat:(NSString *)strings, ...
{
va_list args;
va_start(args, strings);
NSString *s;
NSString *con = [self stringByAppendingString:strings];
while((s = va_arg(args, NSString *)))
con = [con stringByAppendingString:s];
va_end(args);
return con;
}
@end
// NSString+ConcatenationTest.h
#import <SenTestingKit/SenTestingKit.h>
#import "NSString+Concatenation.h"
@interface NSString_ConcatenationTest : SenTestCase
@end
// NSString+ConcatenationTest.m
#import "NSString+ConcatenationTest.h"
@implementation NSString_ConcatenationTest
- (void)testSimpleConcatenation
{
STAssertEqualObjects([@"a":@"b"], @"ab", nil);
STAssertEqualObjects([@"a":@"b":@"c"], @"abc", nil);
STAssertEqualObjects([@"a":@"b":@"c":@"d"], @"abcd", nil);
STAssertEqualObjects([@"a":@"b":@"c":@"d":@"e"], @"abcde", nil);
STAssertEqualObjects([@"this " : @"is " : @"string " : @"concatenation"],
@"this is string concatenation", nil);
}
- (void)testVarArgConcatenation
{
NSString *concatenation = [@"a" concat:@"b", nil];
STAssertEqualObjects(concatenation, @"ab", nil);
concatenation = [concatenation concat:@"c", @"d", concatenation, nil];
STAssertEqualObjects(concatenation, @"abcdab", nil);
}
RE: Shortcuts in Objective-C to concatenate NSStrings - equations151689 - 07-21-2023
Two answers I can think of... neither is particularly as pleasant as just having a concatenation operator.
First, use an `NSMutableString`, which has an `appendString` method, removing some of the need for extra temp strings.
Second, use an `NSArray` to concatenate via the `componentsJoinedByString` method.
RE: Shortcuts in Objective-C to concatenate NSStrings - bathyscapheseddfh - 07-21-2023
How about shortening `stringByAppendingString` and use a **#define**:
#define and stringByAppendingString
Thus you would use:
NSString* myString = [@"Hello " and @"world"];
Problem is that it only works for two strings, you're required to wrap additional brackets for more appends:
NSString* myString = [[@"Hello" and: @" world"] and: @" again"];
RE: Shortcuts in Objective-C to concatenate NSStrings - empathises393976 - 07-21-2023
Here's a simple way, using the new array literal syntax:
NSString * s = [@[@"one ", @"two ", @"three"] componentsJoinedByString:@""];
^^^^^^^ create array ^^^^^
^^^^^^^ concatenate ^^^^^