Objective-C中的字符串比较

Question

我目前有一个网络服务器设置,我通过SOAP与我的iPhone应用程序进行通信.我正在返回一个包含GUID的字符串,当我尝试将其与另一个字符串进行比较时,我得到一些奇怪的结果.

为什么这不会开火？当然这两个字符串是匹配的吗？

NSString *myString = @"hello world";

if(myString == @"hello world")
    return;

Answer 1

使用该-isEqualToString:方法比较两个字符串的值.使用C ==运算符将简单地比较对象的地址.

if ([category isEqualToString:@"Some String"])
{
    // Do stuff...
}

Answer 2

您可以根据需要使用区分大小写或不区分大小写的比较.区分大小写是这样的:

if ([category isEqualToString:@"Some String"])
{
   // Both strings are equal without respect to their case.
}

不区分大小写是这样的:

if ([category compare:@"Some String" options:NSCaseInsensitiveSearch] == NSOrderedSame)
{
   // Both strings are equal with respect to their case.
}

Answer 3

您可以将字符串与以下函数进行比较。

NSString *first = @"abc";
NSString *second = @"abc";
NSString *third = [[NSString alloc] initWithString:@"abc"];
NSLog(@"%d", (second == third))  
NSLog(@"%d", (first == second)); 
NSLog(@"%d", [first isEqualToString:second]); 
NSLog(@"%d", [first isEqualToString:third]); 

Output will be :-
    0
    1
    1
    1