如何在NSArray中找到某种对象？

for (id obj in array) {
    if ([obj isKindOfClass:[DesiredClass class]]) {
        // 找到了所需的对象
    }
}

NSPredicate *predicate = [NSPredicate predicateWithFormat:@"self isKindOfClass:%@", [DesiredClass class]];
NSArray *filteredArray = [array filteredArrayUsingPredicate:predicate];

NSIndexSet *indexes = [array indexesOfObjectsPassingTest:^BOOL(id obj, NSUInteger idx, BOOL *stop) {
    return [obj isKindOfClass:[DesiredClass class]];
}];
NSArray *filteredArray = [array objectsAtIndexes:indexes];