NSPredicate驗證：a-z，0-9和下劃線

Question

我想只允許a-z，0-9和_（下劃線），但它不能正常工作。

NSString *test = @"name_test09"; // should be valid 
NSPredicate *predicate = [NSPredicate predicateWithFormat:@"SELF MATCHES %@", @"[a-z0-9_]"]; 

if ([predicate evaluateWithObject:test] == NO) { 
    // not validated 
} else { 
    // validated 
} 

Answer 1

它應該是。

NSPredicate *pred = [NSPredicate predicateWithFormat:@"SELF MATCHES[c] %@", @"[a-z][0-9]_"]; 

MY編輯：

NSString *s =@"abcdefghijklmnopqrstuvwxyz1234567890_"; 
NSPredicate *pred = [NSPredicate predicateWithFormat:@"SELF MATCHES[c] %@",s]; 

或

NSString *myRegex = @"[a-z0-9_]*"; 
NSPredicate *myTest = [NSPredicate predicateWithFormat:@"SELF MATCHES %@", myRegex]; 
BOOL valid = [myTest evaluateWithObject: test]; 
if (valid) 
{ 
} 
else 
{ 
}