oc7

来源：互联网发布：09霍华德vs詹姆斯数据编辑：程序博客网时间：2024/05/21 09:20

//__block可以在Block中修改变量。typedef int (^Block) (int);Block b = ^(int n) {    return 2;};//在非函数中,先声明，在赋值是错误的，在函数中正确Block b1;b1 = ^(int n) {    return 3;}; void test() {    Block b2;    b2 = ^(int n) {        return 3;    };}

block回调函数。

if (btnrespondsToSelector:@selector(xxx))

if(btn conformsToProtocol:<#(Protocol*)#>)

stu->age; //直接访问成员变量

NSError *error;

NSString *str = @”1231321”;

[str hasPrefix:@”123”] //是否以xx开头

[str hasSuffix:@”21”] //是否以xx结尾；

[str rangeFromString:@”313” options:];

[str substringFromIndex:3];//12321

[str substringToIndex:2]; //12

[str substringWirhRange:range];

[str componentsSeparatedByString:@””];

NSString *path =[NSStringpathWithComponents:array];//拼接成路径

[path pathComponents]; //路径转换为数组

[path isAbsolutePath];

[path lastPathComponent];

[path stringByDeletingLastPathComponent];

[path stringByAppendingPathComponent:@”aa”];

[str pathExtension] //返回扩展名

const char *str = [@"ab"UTF8String];//C字符串

 /*疑惑    NSArray说是不可变数组，视屏中讲到与NSMutableArray中差别，讲了NSMutableArray有addObject:方法，可以向可变数组添加元素，而说NSArray没有着方法，就不可添加。     但是NSArray也有arrayByAddingObjec:,arrayByAddingObject:方法，可以向数组添加元素，感觉视屏中讲的就有些不对了。     求解惑。     */    //解决：arrayByAddingObject：返回一个新的对象    NSArray *array = [NSArray array];    array = [array arrayByAddingObject:@"xg"];    NSLog(@"%p",array);    array = [array arrayByAddingObject:@"xy"];    NSLog(@"%p",array);    NSMutableArray *array1 = [NSMutableArray array];    [array1 addObject:@"dada"];    [array1 addObject:@"dadasa"];    NSLog(@"%p",array1);

    NSArray *array2 = [NSArray arrayWithObjects:@"xx", @"xm", nil];array= [array arrayByAddingObjectsFromArray:(array2)];//枚举遍历    NSEnumerator*enumerator = [array objectEnumerator];    NSEnumerator*reEnumerator = [array reverseObjectEnumerator];    id obj = nil;    while (obj =[enumerator nextObject]) {        NSLog(@"obj=%@",obj);    }

[array containsObject:<#(id)#>]

[array makeObjectsPerformSelector:@selector(test :)withObject:@"123"];

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