请使用此代码

NSString *string = @"hello bla bla";
if ([string rangeOfString:@"bla"].location == NSNotFound) 
{
    NSLog(@"string does not contain bla");
} 
else 
{  
    NSLog(@"string contains bla!");
}

所以我个人非常讨厌NSNotFound，但是理解它的必要性。

但是有些人可能不理解与NSNotFound比较的复杂性

例如，下面的代码:

- (BOOL)doesString:(NSString*)string containString:(NSString*)otherString {
    if([string rangeOfString:otherString].location != NSNotFound)
        return YES;
    else
        return NO;
}

有它的问题:

1)显然，如果otherString = nil这段代码将崩溃。一个简单的测试是:

NSLog(@"does string contain string - %@", [self doesString:@"hey" containString:nil] ? @"YES": @"NO");

结果!!崩溃! !

2)对于objective-c的新手来说，不太明显的是，当string = nil时，相同的代码不会崩溃。 例如，下面的代码:

NSLog(@"does string contain string - %@", [self doesString:nil containString:@"hey"] ? @"YES": @"NO");

这段代码:

NSLog(@"does string contain string - %@", [self doesString:nil containString:nil] ? @"YES": @"NO");

都会导致

does string contains string - YES

这显然不是你想要的。

所以我认为更好的解决方案是使用rangeOfString返回0的长度，然后一个更好更可靠的代码是这样的:

- (BOOL)doesString:(NSString*)string containString:(NSString*)otherString {
    if(otherString && [string rangeOfString:otherString].length)
        return YES;
    else
        return NO;
}

或者仅仅是:

- (BOOL)doesString:(NSString*)string containString:(NSString*)otherString {
    return (otherString && [string rangeOfString:otherString].length);
}

对于情况1和2哪种会返回

does string contains string - NO

这是我的2美分;-)

请查看我的Gist以获得更多有用的代码。

NSString *myString = @"hello bla bla";
NSRange rangeValue = [myString rangeOfString:@"hello" options:NSCaseInsensitiveSearch];

if (rangeValue.length > 0)
{
    NSLog(@"string contains hello");
} 
else 
{
    NSLog(@"string does not contain hello!");
}

//你也可以使用下面的语句:

if (rangeValue.location == NSNotFound) 
{
    NSLog(@"string does not contain hello");
} 
else 
{
    NSLog(@"string contains hello!");
}

联机(更少的代码。DRY，因为你只有一个NSLog):

NSString *string = @"hello bla bla";
NSLog(@"String %@", ([string rangeOfString:@"bla"].location == NSNotFound) ? @"not found" : @"cotains bla"); 

下面是一个复制粘贴函数片段:

-(BOOL)Contains:(NSString *)StrSearchTerm on:(NSString *)StrText
{
    return [StrText rangeOfString:StrSearchTerm 
        options:NSCaseInsensitiveSearch].location != NSNotFound;
}

i的解决方案的一个改进版本，NSString上的一个类别，它不仅会告诉，如果一个字符串在另一个字符串中被找到，而且还需要一个引用范围，是:

@interface NSString (Contains)
-(BOOL)containsString: (NSString*)substring
              atRange:(NSRange*)range;

-(BOOL)containsString:(NSString *)substring;
@end

@implementation NSString (Contains)

-(BOOL)containsString:(NSString *)substring
              atRange:(NSRange *)range{

    NSRange r = [self rangeOfString : substring];
    BOOL found = ( r.location != NSNotFound );
    if (range != NULL) *range = r;
    return found;
}

-(BOOL)containsString:(NSString *)substring
{
    return [self containsString:substring
                        atRange:NULL];
}

@end

像这样使用它:

NSString *string = @"Hello, World!";

//If you only want to ensure a string contains a certain substring
if ([string containsString:@"ello" atRange:NULL]) {
    NSLog(@"YES");
}

// Or simply
if ([string containsString:@"ello"]) {
    NSLog(@"YES");
}

//If you also want to know substring's range
NSRange range;
if ([string containsString:@"ello" atRange:&range]) {
    NSLog(@"%@", NSStringFromRange(range));
}