我知道我不久前问了一个类似的问题,但我仍然有点不确定.同样的事情发生在几个地方.
‘self’时使用的实例变量未设置为'[(super或self)init …]的结果
- (id)initWithCoder:(NSCoder *)decoder { if (![super init]) return nil; red = [decoder decodeFloatForKey:kRedKey]; //occurs here green = [decoder decodeFloatForKey:kGreenKey]; blue = [decoder decodeFloatForKey:kBlueKey]; return self; }
乙
- (id)initWithFrame:(CGRect)frame title:(Nsstring*)str sideUp:(BOOL)up{ if(![super initWithFrame:frame]) return nil; int y; UIImage *img; if(up){ img = [UIImage imageNamedTK:@"TapkuLibrary.bundle/Images/graph/popup"]; y = 5; }else{ img = [UIImage imageNamedTK:@"TapkuLibrary.bundle/Images/graph/popdown"]; y = 14; } background = [[UIImageView alloc] initWithImage:img]; // occurs here
C
- (id) initWithFrame:(CGRect)frame { if(![super initWithFrame:frame]) return nil; UILabel *titleBackground = [[[UILabel alloc] initWithFrame: CGRectMake(0,480,40)] autorelease]; titleBackground.backgroundColor = [UIColor whiteColor]; [self addSubview:titleBackground]; titleLabel = [[UILabel alloc] initWithFrame:CGRectZero]; // occurs here
对于块A,这是正确的
self = [self init]; if( self != nil ) {
和B& C
- (id) initWithFrame:(CGRect)frame { super = [super initWithFrame:frame] if(super != nil) {
解决方法
一般来说,你应该写:
self = [super init...]; // Potentially change "self" if (self) { something = x; another = y; } return self;
这是因为在某些情况下init可能不会返回原始的self值.