objective-c - NSString isEqualToString 不会返回 true，并且无法识别选择器

Question

我有一个字符串 dummyString 需要与 100 进行比较。这是我的代码

  dummyString = [prefs objectForKey:@"displaySize"];
[self setDisplaySize:dummyString];
NSLog(@"Getting ready to set display controller with value %@", dummyString);


NSLog(@"Tried 1");
if ([dummyString isEqual: @"5"]) {
    NSLog(@"Loaded preferences, display Small");
    displayChanged.selectedSegment = 0;}

NSLog(@"Tried 2");
if ([dummyString isEqual: @"40"]){
    NSLog(@"Loaded preferences, display is Med!");
        displayChanged.selectedSegment = 1;}

NSLog(@"Tried 3");
if ([dummyString isEqualToString:@"100"]){
    NSLog(@"Loaded preferences, display LARGE");
    displayChanged.selectedSegment = 2;}

NSLog(@"Completed trying to get display controller with value %@", dummyString);

这是 NSLog

2013-03-26 17:22:49.101 CopyBot[1011:303] Getting ready to set display controller with value 100
 2013-03-26 17:22:49.102 CopyBot[1011:303] Tried 1
 2013-03-26 17:22:49.102 CopyBot[1011:303] Tried 2
 2013-03-26 17:22:49.102 CopyBot[1011:303] Tried 3
 2013-03-26 17:22:49.103 CopyBot[1011:303] -[__NSCFNumber isEqualToString:]: unrecognized selector sent to instance 0x64c7
 2013-03-26 17:22:49.103 CopyBot[1011:303] -[__NSCFNumber isEqualToString:]: unrecognized selector sent to instance 0x64c7

我尝试了一些声明不同字符串的变体，但似乎无法输入“if”语句来进行 isEqual 或 isEqualToString 的任何比较。如有任何帮助，我们将不胜感激。

Answer 1

根据您的错误，您的 dummyString 不是 NSString 实际上它是 NSNumber。

您可以将字符串 @"5" 转换为 NSNumber，然后进行比较:

BOOL equal=[dummyString isEqualToNumber:@([@"5" integerValue])];

或者。将虚拟字符串值转换为字符串，然后进行比较:

BOOL equal=[NSString stringWithFormat:@"%d",[dummyString integerValue]] isEqualToString:@"5"];