//遍历所有的子控件，并打印其Frame

+(NSString )searchAllSubviews:(UIView )superview

{

NSMutableString xml = [NSMutableString];

NSString class = NSStringFromClass( superview.class );

class = [class stringByReplacingOccurrencesOfString: @"_" withString: @""];

[xml appendFormat:@"<%@ frame = "%@">\n" , class, NSStringFromCGRect( superview.frame)];

for (UIView child in super.subviews){

NSString subViewXml = [self searchAllSubviews : childView];

[xml appendString : subviewXml];

}

[xml appendFormat :@"<%@>\n",class];

return xml;

}

block外的变量不能在block中修改

若想改变则应在变量前加上__block