常见问题缺陷与解决办法
1.Returning 'self' while it is not set to the result of '[(super or self) init...]
self 未被赋值 就被返回；
错误：-(instancetype)init{
if(self ==[super init])
{
}
return self;
}
正确：
-(instancetype)init{
self =[super init]
if(self)
{
}
return self;
}
2.Instance variable used while 'self' is not set to the result of '[(super or self) init...]'
self 未被赋值就使用了实例变量
错误：-(id)initWithIdentifier:(NSString*)identifier
{
if(self== [superinit]) {
_cellIdentifier= identifier;
}
returnself;
}
正确：-(id)initWithIdentifier:(NSString*)identifier
{
self= [super init];
if(self) {
_cellIdentifier= identifier;
}
return self;
}
3.The ‘viewWillAppear:’ instance method in UIViewController subclass ‘YourViewController’ is missing a [super viewWillAppear:] call
实例化子类YourViewController 未调用[super viewWillAppear:]
错误：-(void)viewWillAppear:(BOOL)animated
{
}
正确：
-(void)viewWillAppear:(BOOL)animated
{
[super viewWillAppear:animated];
}
4.Undefined or garbage value returned to caller 返回了垃圾值或未被定义的值。
//分区头高度
错误：-(CGFloat)tableView:(UITableView*)tableView heightForHeaderInSection:(NSInteger)section
{
CGFloat headerHeight
return headerHeight;
}
正确：-(CGFloat)tableView:(UITableView*)tableView heightForHeaderInSection:(NSInteger)section
{
CGFloat headerHeight = 0.000001；
return headerHeight;
}
5.The left expression of the compound assignment is an uninitialized value. The computed value will also be garbage 复合表达式 左边的值未被初始化，计算了也是垃圾值
错误：+(float)folderSizeAtPath{
float folderSize
folderSize+=4;
return folderSize;
}
正确：+(float)folderSizeAtPath{
float folderSize = 0；
folderSize+=4;
return folderSize;
}
6.Passed-by-value struct argument contains uninitialized data 参数中包含了未被初始化的结构体
错误：- (NSRange *)firstParagraph
{
NSRange range ;
return [self range:range];
}
正确：- (NSRange *)firstParagraph
{
NSRange range =NSMakeRange(0,0);
return [self range:range];
}