Question

@interface Set : NSObject
{
// instance variables
int repetitions;
int weight;
}
// functions
- (id)init;
- (id)initWithReps: (int)newRepetitions andWeight: (int)newWeight;

@implementation Set
-(id)init
{
if (self = [super init]) {
    repetitions = 0;
    weight = 0;
}
return self;
}

-(id)initWithReps: (int)newRepetitions andWeight: (int)newWeight
{
if (self = [super init]) 
{
    repetitions = newRepetitions;
    weight = newWeight;
}
return self;
}

@implementation eFit2Tests

- (void)setUp
{
[super setUp];
// Set-up code here.
}

- (void)tearDown
{
// Tear-down code here. 
[super tearDown];
}

- (void)testInitWithParam
{
Set* test = nil;
test = [test initWithReps:10 andWeight:100];
NSLog(@"Num Reps: %d", [test reps]);
if([test reps] != 10) {
    STFail(@"Reps not currectly initialized. (initWithParam)");
}
NSLog(@"Weight: %d", [test weight]);
if([test weight] != 100) {
    STFail(@"Weight not currectly initialized. (initWithParam)");
}
}

由于某些原因，此代码段底部的测试失败，因为重复和权重的值总是等于0.我来自Java的背景，并且对于为什么会这样，我一无所知。抱歉这个愚蠢的问题......

Answer 1

您将test设置为nil，然后发送initWithReps:andWeight:。这相当于[nil initWithReps:10 andWeight:100]，这显然不是你想要的。 nil只响应任何带有自身或0的消息，因此init消息返回nil并且将reps发送给nil返回0.

要创建对象，您需要alloc类方法 - 即Set *test = [[Set alloc] initWithReps:10 andWeight:100]。（如果您没有使用ARC，根据内存管理指南，您将需要在完成后释放此对象。）

Answer 2

如果您要初始化设置，请将其替换为：

Set *test = [[Set alloc] initWithReps: 10 andWeight: 100];

你得到0是因为它是来自nil对象的默认返回（你初始化测试为nil） - Objective-C中没有NullPointerExceptions

Objective-C init函数未正确初始化

2 个答案: