Objective-C中连接NSString的快捷方式

Objective-C中是否有（

stringByAppendingString:

）字符串连接的快捷方式，或者通常使用

NSString

的快捷方式

例如，我想：

NSString *myString = @"This";
NSString *test = [myString stringByAppendingString:@" is just a test"];

更像是：

string myString = "This";
string test = myString + " is just a test";

---

我能想到两个答案。。。两者都不如仅仅拥有一个串联操作符那么令人愉快

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要

---

其次，使用

NSArray

通过

componentsJoinedByString

方法连接。

使

c=[a stringByAppendingString:b]

更短的唯一方法是在

st

点附近使用autocomplete。

+

操作符是C的一部分，它不知道Objective-C对象。

一个选项： 另一种选择： 我猜您对多个附件（a+b+c+d）不满意，在这种情况下，您可以：

NSLog(@"%@", [Util append:one, @" ", two, nil]); // "one two"
NSLog(@"%@", [Util append:three, @"/", two, @"/", one, nil]); // three/two/one

使用类似

+ (NSString *) append:(id) first, ...
{
    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);
    }
    return result;
}

---

创建AppendString（AS）宏的快捷方式…

#define AS(A,B) [(A) stringByAppendingString:(B)]
NSString *myString = @"This"; NSString *test = AS(myString,@" is just a test"); #定义为（A，B）[（A）字符串通过附加字符串：（B）]
NSString*myString=@“This”； NSString*test=AS（myString，@“只是一个测试”）； 注意：

// 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:@""]

- (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");
}

---

如果使用宏，当然只需使用可变参数即可，请参见EthanB的答案。

使用

stringByAppendingString:

，方法如下：

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];

NSString *string1, *string2, *result;

string1 = @"This is ";
string2 = @"my string.";

result = [result stringByAppendingString:string1];
result = [result stringByAppendingString:string2];

或

---

如果您有两个NSString文本，也可以这样做：

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

这对于连接也很有用#定义：

---

享受

这是为了更好地记录日志，并且仅记录日志-基于dicius优秀的多参数方法。我定义了一个Logger类，并这样称呼它：

[Logger log: @"foobar ", @" asdads ", theString, nil];

几乎不错，除了必须以“nil”结束var args，但我想在Objective-C中没有办法解决这个问题

记录器.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 http://stackoverflow.com/questions/510269/how-do-i-concatenate-strings-in-objective-c
    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 

为了只处理concat字符串，我将在NSString上定义一个类别，并向其添加一个静态（+）concatenate方法，该方法与上面的log方法完全相同，只是它返回字符串。它位于NSString上，因为它是一个string方法，而它是静态的，因为您希望从1-N个字符串创建一个新字符串，而不是在属于append的任何一个字符串上调用它

创建一个方法：

- (NSString *)strCat: (NSString *)one: (NSString *)two
{
    NSString *myString;
    myString = [NSString stringWithFormat:@"%@%@", one , two];
    return myString;
}

然后，在任何需要它的函数中，将字符串或文本字段或任何内容设置为该函数的返回值

---

或者，为了快捷方式，将NString转换成C++字符串，使用“+”，.< /P> < P>，冒号是特殊符号，但是方法签名的一部分，可以使用类别“<代码> NString < /Cord> >添加这个“强>非惯用< /强>字符串连接样式：

[@"This " : @"feels " : @"almost like " : @"concatenation with operators"];

您可以定义尽可能多的冒号分隔参数，只要您觉得有用…；-）

为了更好地衡量，我还添加了

concat:

，其中包含变量参数，这些参数接受

nil

终止的字符串列表

//  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);
}

//NSString+Concatenation.h
#进口
@接口字符串（连接）
-（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*）字符串。。。；
@结束
//NSString+Concatenation.m
#导入“NSString+Concatenation.h”
@实现NSString（串联）
-（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*）字符串。。。
{
va_列表参数；
va_开始（参数、字符串）；
NSString*s；
NSString*con=[self-stringByAppendingString:strings]；
而（（s=va_arg（args，NSString*））
con=[con stringByAppendingString:s]；
va_端（args）；
返回con；
}
@结束
//NSString+ConcatenationTest.h
#进口
#导入“NSString+Concatenation.h”
@接口NSString\u连接测试：SenTestCase
@结束
//NSString+ConcatenationTest.m
#导入“NSString+ConcatenationTest.h”
@NSString\U连接测试的实现
-（void）TestSimpleContainement
{
STAssertEqualObjects（[@“a”：@“b”]，@“ab”，无）；
STAssertEqualObjects（[@“a”：“b”：“c”]，@“abc”，无）；
STAssertEqualObjects（[@“a”：“b”：“c”：“d”]，@“abcd”，无）；
STAssertEqualObjects（[@“a”：“b”：“c”：“d”：“e”]，“abcde”，无）；
STAssertEqualObjects（[@“this”：@“is”：@“string”：@“concatenation”]，
@“这是字符串连接”，nil）；
}
-（void）testVarArgConcatenation
{
NSString*串联=[@“a”concat:@“b”，nil]；
STAssertEqualObjects（串联，@“ab”，nil）；
级联=[级联concat:@“c”，@“d”，级联，nil]；
STAssertEqualObjects（串联，@“abcdab”，nil）；
}

在构建web服务请求时，我发现执行以下操作非常简单，并且可以在Xcode中读取连接：

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>"
};

NSString*postBody={
@""
@""
@" "
@"  "
@“测试”
@"  "
@" "
@""
};

如何通过添加字符串来缩短

字符串，并使用\define：

#define and stringByAppendingString

因此，您将使用：

NSString* myString = [@"Hello " and @"world"];

问题是，它只适用于两个字符串，您需要为更多的附录包装额外的括号：

NSString* myString = [[@"Hello" and: @" world"] and: @" again"];

我一直回到这篇文章，最后总是对答案进行排序，以找到这个简单的解决方案，它可以根据需要处理尽可能多的变量：

[NSString stringWithFormat:@"%@/%@/%@", three, two, one];

例如：

NSString *urlForHttpGet = [NSString stringWithFormat:@"http://example.com/login/username/%@/userid/%i", userName, userId];

下面是一种使用新数组文字语法的简单方法：

NSString * s = [@[@"one ", @"two ", @"three"] componentsJoinedByString:@""];
                  ^^^^^^^ create array ^^^^^
                                               ^^^^^^^ concatenate ^^^^^

尝试stringWithFormat：

NSString *myString = [NSString stringWithFormat:@"%@ %@ %@ %d", "The", "Answer", "Is", 42];

在处理字符串时，我发现使源文件ObjC++更容易，然后可以使用问题中所示的第二种方法连接std:：strings

std::string stdstr = [nsstr UTF8String];

//easier to read and more portable string manipulation goes here...

NSString* nsstr = [NSString stringWithUTF8String:stdstr.c_str()];

您可以使用NSArray作为

NSString *string1=@"This"

NSString *string2=@"is just"

NSString *string3=@"a test"  

NSArray *myStrings = [[NSArray alloc] initWithObjects:string1, string2, string3,nil];

NSString *fullLengthString = [myStrings componentsJoinedByString:@" "];

或

std::string stdstr = [nsstr UTF8String];

//easier to read and more portable string manipulation goes here...

NSString* nsstr = [NSString stringWithUTF8String:stdstr.c_str()];

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

NSString *string1=@"This"

NSString *string2=@"is just"

NSString *string3=@"a test"  

NSArray *myStrings = [[NSArray alloc] initWithObjects:string1, string2, string3,nil];

NSString *fullLengthString = [myStrings componentsJoinedByString:@" "];

NSString *imageFullName=[NSString stringWithFormat:@"%@ %@ %@.", string1,string2,string3];

NSString *result=[NSString stringWithFormat:@"%@ %@", @"Hello", @"World"];

NSString *firstString = @"foo";
NSString *secondString = @"bar";
NSString *thirdString = @"baz";

NSString *joinedString = [@[firstString, secondString, thirdString] join];

#import "NSArray+Join.h"
@implementation NSArray (Join)
-(NSString *)join
{
    return [self componentsJoinedByString:@""];
}
@end

NSString *joinedString = [@[firstString, secondString, thirdString] componentsJoinedByString:@""];

NSMutableString * myString=[[NSMutableString alloc]init];
myString=[myString stringByAppendingString:@"first value"];
myString=[myString stringByAppendingString:@"second string"];

// 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:@""]

- (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");
}

// 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:@""];

NSString *myString = @"This";
NSString *test = [myString stringByAppendingString:@" is just a test"];

[NSString stringWithFormat:@"%@/%@/%@", three, two, one];

[[NSString alloc] initWithFormat:@"%@/%@/%@", @"three", @"two", @"one"];

NSNumber *lat = [NSNumber numberWithDouble:destinationMapView.camera.target.latitude];
NSNumber *lon = [NSNumber numberWithDouble:destinationMapView.camera.target.longitude];
NSString *DesconCatenated = [NSString stringWithFormat:@"%@|%@",lat,lon];

NSString *sTest1 = {@"This" " and that" " and one more"};
NSString *sTest2 = {
  @"This"
  " and that"
  " and one more"
};

NSLog(@"\n%@\n\n%@",sTest1,sTest2);

NSMutableArray *arrForStrings = [[NSMutableArray alloc] init];
for (int i=0; i<[allMyStrings count]; i++) {
    NSString *str = [allMyStrings objectAtIndex:i];
    [arrForStrings addObject:str];
}
NSString *readyString = [[arrForStrings mutableCopy] componentsJoinedByString:@", "];

-(void) clearTextField:(XCUIElement*) textField{

    NSString* currentInput = (NSString*) textField.value;
    NSMutableString* deleteString = [NSMutableString new];

    for(int i = 0; i < currentInput.length; ++i) {
        [deleteString appendString: [NSString stringWithFormat:@"%c", 8]];
    }
    [textField typeText:deleteString];
}

#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 ?: @""];

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