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];

宏:

// stringConcat(...)
//     A shortcut for concatenating strings (or objects' string representations).
//     Input: Any number of non-nil NSObjects.
//     Output: All arguments concatenated together into a single NSString.

#define stringConcat(...) \
    [@[__VA_ARGS__] componentsJoinedByString:@""]

测试用例:

- (void)testStringConcat {
    NSString *actual;

    actual = stringConcat(); //might not make sense, but it's still a valid expression.
    STAssertEqualObjects(@"", actual, @"stringConcat");

    actual = stringConcat(@"A");
    STAssertEqualObjects(@"A", actual, @"stringConcat");

    actual = stringConcat(@"A", @"B");
    STAssertEqualObjects(@"AB", actual, @"stringConcat");

    actual = stringConcat(@"A", @"B", @"C");
    STAssertEqualObjects(@"ABC", actual, @"stringConcat");

    // works on all NSObjects (not just strings):
    actual = stringConcat(@1, @" ", @2, @" ", @3);
    STAssertEqualObjects(@"1 2 3", actual, @"stringConcat");
}

备用宏:(如果你想强制一个最小数量的参数)

// stringConcat(...)
//     A shortcut for concatenating strings (or objects' string representations).
//     Input: Two or more non-nil NSObjects.
//     Output: All arguments concatenated together into a single NSString.

#define stringConcat(str1, str2, ...) \
    [@[ str1, str2, ##__VA_ARGS__] componentsJoinedByString:@""];

如果你有两个NSString字面量，你也可以这样做:

NSString *joinedFromLiterals = @"ONE " @"MILLION " @"YEARS " @"DUNGEON!!!";

这对于加入#定义也很有用:

#define STRINGA @"Also, I don't know "
#define STRINGB @"where food comes from."
#define JOINED STRINGA STRINGB

享受。

我能想到两个答案……这两种方法都没有使用连接运算符那么令人愉快。

首先，使用一个NSMutableString，它有一个appendString方法，消除了对额外临时字符串的一些需求。

其次，使用NSArray通过componentsJoinedByString方法进行连接。

受Chris的NSMutableString想法的启发，我做了一个完美的宏。 它支持插入nil元素，没有任何异常。

#import <libextobjc/metamacros.h>

#define STR_CONCAT(...) \
    ({ \
        __auto_type str__ = [NSMutableString string]; \
        metamacro_foreach_cxt(never_use_immediately_str_concatify_,, str__, __VA_ARGS__) \
        (NSString *)str__.copy; \
    })

#define never_use_immediately_str_concatify_(INDEX, CONTEXT, VAR) \
    [CONTEXT appendString:VAR ?: @""];

例子:

STR_CONCAT(@"button_bg_", @(count).stringValue, @".png"); 
// button_bg_2.png

如果你喜欢，你可以使用id类型作为参数使用[VAR description]而不是NSString。

listOfCatalogIDs =[@[@"id[]=",listOfCatalogIDs] componentsJoinedByString:@""];